It uses a regular expression pattern as the first argument. Fourier transform of a propagating Dirac delta, Calling external applications/bat files using QGIS Graphical Modeller. Is there a word that's the relational opposite of "Childless"? And just like the includes() method, the indexOf() method is case-sensitive. Garage door suddenly really heavy, opener gives up. Search Array Elements For Substring and return index, How to find specific line of data in array, Excluding Punctuation Marks in JavaScript include method. Remember, the first letter in a string has a position of 0, the second a position of 1, and so on. For example, if the string is Hello World, then the substring could be Hello or World. Our mission: to help people learn to code for free. How do I remove a property from a JavaScript object? The String.includes () provides the most simple and popular way to check if a string contains a substring in modern JavaScript. The String.search() method searches the position of the substring in a string and returns the position of the match. consider buying me a coffee ($5) or two ($10). Ex: myArray[newVar]. Definition and Usage finding substrings within arrays - javascript. Try it Syntax indexOf(searchString) indexOf(searchString, position) Parameters searchString Substring to search for. The method takes 2 arguments: the start index and the end index. were not answering my questions. You need two nested loop for the sub strings. console.log() method displays -1. The find () is a string method that finds a substring in a string and returns the index of the substring. Start with a Learn more about Teams This method also takes 2 arguments: the start index and the end index. It is 2 1/2 inches wide and 1 1/2 tall. Substring to search for. Can we apply stepwise forward or backward variables selection in negative binomial regression in SPSS? How do I find the position of a substring within a string starting at a position somewhere in the middle of the string? I need to search an array in JavaScript. How many numbers can I generate and be 90% sure that there are no duplicates. It was introduced in ES6 and works in all modern browsers except Internet Explorer. Let's start with the substring ( ) method. It is important to be able to find substrings in strings because it can be used in many different ways. Can we apply stepwise forward or backward variables selection in negative binomial regression in SPSS? Is it possible to determine a maximum L/D possible. It's a free, well-thought-out, and structured curriculum where you will learn interactively. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @zzzzBov Your comment is worth an answer, This is EXACTLY what I needed, and a great modern answer. what is the best way to check if a string exists in another? I googled javascript substring index and the following showed up: What is the relationship between the returned result. "+", "?". Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Any Idea? This method takes the substring as a parameter and returns a boolean, true if the substring is found in the string and false if it is not. In Typescript, there are several different ways to find a substring in a string. 1. @wz366 KMP provides O(n), what about the rest? To learn more, see our tips on writing great answers. Say you want to start your search from position 1. Note: The includes() method is case sensitive. But, none are working for me. The search value can be a string or a regular expression. "cheddar" is not found in myCapString, so the second Convert both the main string and the substring to lower or upper case before using includes(). Just search for the string in plain old indexOf, The simplest vanilla javascript code to achieve this is. This method takes a regular expression as a parameter and returns an array of all the substrings that match the pattern. The first console.log() method displays 19. In this example, the includes() method checks if the "Python" element is present in the programmingLanguages array. Does a Wildfire Druid actually enter the unconscious condition when using Blazing Revival? Find centralized, trusted content and collaborate around the technologies you use most. In this case I used ES6 syntax to declare the higher order function. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Previous JavaScript String Reference Next Examples Extract a substring from text: let text = "Hello world!"; let result = text.substring(1, 4); Try it Yourself Start from position 2: let result = text.substring(2); Try it Yourself More examples below. Slanted Brown Rectangles on Aircraft Carriers? Are interstellar penal colonies a feasible idea? How to find exact substring inside a string using javascript [duplicate]. Below is a simple approach to find all substrings. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. How to Generate Random Colors in JavaScript (4 Approaches), 4 Ways to Extract a Substring from a String in JavaScript, JavaScript Regular Expressions Cheat Sheet, Count the occurrences of each word in a string, Remove leading and trailing whitespace from a string, Check if a String Starts or Ends With a Substring, Different Ways to Generate Random Strings, Convert a byte array to a hex string and vice versa, Generate a random number between Min and Max and exclude a specific number, Calculate Variance and Standard Deviation, Define a Function with Default Parameters, Use JavaScript classes to model and validate data, Private, protected, and public class members, Using Arrow Functions in JavaScript Classes, Count the occurrences of elements in an array, Generate an array of random elements with a given length, How to append/prepend/insert elements to an array, Update/Replace a Specific Element in an Array, Remove all occurrences of a value from an array, Check if an array contains a given object, Convert an Array to an Object in JavaScript, Find elements in array A but not in array B, Remove elements that occur in one array from another, Pass an Array to a Function as multiple Arguments, Pass a JavaScript Array within a Query String, Get the Key of an Object Property by Its Value, Create/Access Object Properties with Variable Keys, Checking if a Key/Value Exists in an Object, Create an Object from Arrays of Keys and Values, Convert an Object to a Query String and Vice Versa, Get current date time in yyyy/MM/dd HH:mm:ss format, 2 Ways to Convert a String into a Date Object, Convert Timestamp to Date Time and Vice Versa, Truncate the time portion of a date string, Sorting an Array of Objects by Date Property, Get an array of dates between 2 given dates, Convert a Map object to JSON and vice versa, Programmatically Disable/Enable a Text Input, Show a Custom Context Menu on Right Click, How to Convert a String into an Array in JavaScript, How to Generate Random Colors in JavaScript (4 Approaches), JavaScript: 3 Ways to Find the Product of a Numeric Array, JavaScript: 3 Ways to Create Multiline Strings, Working with Typed Arrays in Modern JavaScript, JavaScript: 4 Ways to Convert a Map into an Object, JavaScript: Add/Remove Key-Value Pairs to/from a Map, JavaScript: Convert a Map object to JSON and vice versa, JavaScript: 4 Ways to Convert an Object to a Map, Working with WeakSet in Modern JavaScript, Working with WeakMap in Modern JavaScript, JavaScript: Convert an Object to a Query String and Vice Versa. Are there military arguments why Russia would blow up the Kakhovka dam? I have updated my answer accordingly. Note: Cut and paste any of the javascript: lines as an immediate mode URI (at least, at most?, in FireFox) to use first javascript: as a URI scheme or protocol and the rest as JS labels. @Gavin by default if I want to know if something is a substring, I imagine it would be case-sensitive. Otherwise, it returns false. rev2023.6.8.43485. Continue with Recommended Cookies. Let's see an example of how the includes() method works. You now know how to check if a string contains a substring in JavaScript. By substring I mean all combinations of letters from the string (do not have to be actual words) So if the string was 'abc' you could have [a, ab, abc, b, ba, bac etc] Thank you for all the responses. Quoting on another level can also be done with the immediate mode javascript protocol URI's below. To learn more about JavaScript, head to freeCodeCamp's JavaScript Algorithms and Data Structures Certification. The newsletter is sent every week and includes early access to clear, concise, and Compare the returned value to -1. It shows error for the '+'. substring S1 is found starting from ith character of S2 Works great. ECMAScript6 introduced String.prototype.includes: String.prototype.includes is case-sensitive and is not supported by InternetExplorer without a polyfill. Connect and share knowledge within a single location that is structured and easy to search. Examples Kusto I need to search for the array element with "id-" in it and I need to pull the rest of the text in the element as well (i.e. Garage door suddenly really heavy, opener gives up. The simplest cloud platform for developers & teams. The String.includes () method returns true if the string contains the specified substring. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Does Python have a string 'contains' substring method? indexOf () method returns an integer representing the index of the first occurrence of string searchStr in the string str. in case of partial phrase). What 'specific legal meaning' does the word "strike" have? A: The includes() method cannot search for elements within nested arrays directly. Null vs Alternative hypothesis in practice. In this article, you will learn two different ways you can check if a string contains a substring using JavaScript methods. In order to give the minimum string length for permutation, Below is a recursive solution to the problem. How to check whether a string contains a substring which is present in a predefined array in JavaScript? It takes an optional starting position and returns the first occurrence of the specified substring at an index greater than or equal to the specified number. Try it Syntax substring(indexStart) substring(indexStart, indexEnd) Parameters indexStart The index of the first character to include in the returned substring. Let's change the value of substring from H to Hello: The return value is again 0 since index0f() returns the starting position of the substring you are looking for. that IMO may make sense if you can have a special char delimiter (here i used "! Then use .indexOf() method to extract the index of the given term -1. How do I accomplish this using jquery/javascript? Asking for help, clarification, or responding to other answers. If no separator is supplied, the split () returns an array with only one element - the original string. Let's use the same example from earlier to see how the indexOf() method works. Upvote! Otherwise, it returns false. Find centralized, trusted content and collaborate around the technologies you use most. Get Second to last character position from string using jQuery, Find substring position into string with Javascript, get substring between two indexes using indexOf(). Consider this code, Code 1) Extracting a substring from the beginning of the string example The following example uses the substring method to extract a substring starting from the beginning of the string: let str = 'JavaScript Substring' ; let substring = str.substring ( 0, 10 ); console .log (substring); Code language: JavaScript (javascript) Output: JavaScript For more information and examples, check out the official MDN Web Docs and Array.prototype.includes() documentation. There are multiple ways to check if a string contains a substring in JavaScript. If the loop terminates after matching all the characters, then return i, i.e. Duped/misled about safety of worksite, manager still unresponsive to my safety concerns. Check a certain section of string if it contains a substring, Search if a string contains a substring in Javascript (partial search). A: Older browsers might not support the includes() method. Not the answer you're looking for? (Specifically for when trying to categorize an adult). I have tried regEx and match,search,test options. Here, we provided a fromIndex of 1, which means the search for the "JavaScript" element will start at the second element of the programmingLanguages array. The two statements have exactly the same result: A new array with those contents. The start index is inclusive, but the end index is exclusive. Next, I will check if substring is present within string using the includes () method and print the result to the console: let string= "Hello, World"; let substring = "Hello"; console.log(string.includes(substring)); // output // true. Since "Welcome" starts at the first character, the method returns false. def removeprefix( org_str, prefix): if org_str. How to check whether a string contains a substring in JavaScript? Another method to extract a substring is to use the String.prototype.substring() method. What do you mean by "all" the substrings? We also have thousands of freeCodeCamp study groups around the world. Not the answer you're looking for? The solution given here is generic unlike the solution 4556343#4556343, which requires a previous parse to identify a string with which to join(), that is not a component of any of the array strings. */ emphatically elucidates the escaping of quoted literals conflict. Thank them for their work by sharing it on social media. First, I created a variable that holds the string Hello, World - this is the string I want to search through: Next, I created a variable with the substring Hello - this is the substring I want to search for in the original string: Next, I will check if substring is present within string using the includes() method and print the result to the console: The return value was true, meaning Hello is present in the variable string. In the latter instance, the method behaves as if it found an empty string at the end of the calling string. The general syntax for the indexOf() method looks something similar to this: The difference between the two methods is their return value. Are interstellar penal colonies a feasible idea? In addition to String#replace there is also String#replaceAll. ClamAV detected Kaiji malware on Ubuntu instance. A modified version of Accepted Answer. Is it true that the Chief Justice granted royal assent to the Online Streaming Act? After all, "A" and "a" are different characters. The return value was true, meaning Hello is present in the variable string. The start parameter defaults to zero. Does the policy change for AI-generated content affect users who (want to) How do I check if string contains substring? By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. Here is the working example. Ask Question Asked 12 years, 5 months ago Modified 4 months ago Viewed 213k times 102 I need to search an array in JavaScript. If we encounter what appears to be an advanced extraterrestrial technological device, would the claim that it was designed be falsifiable? The includes() method is a built-in JavaScript function that checks if a specific element or substring is present in an array or a string, respectively. Does specifying the optional passphrase after regenerating a wallet with the same BIP39 word list as earlier create a new, different and empty wallet? Test if array contains specific substring, Searching an array for a substring in Javascript. Let's dive into some examples to see how this method works in practice. After processing all these steps it will print the result with the help of variables- org_str and rest_substring. Self-healing code is the future of software development, How to keep your new tool from gathering dust, We are graduating the updated button styling for vote arrows, Statement from SO: June 5, 2023 Moderator Action. (Specifically for when trying to categorize an adult). how to get the different combinations from an array's elements? expression returns -1: When checking if a specific substring occurs within a string, the correct way to check is test whether the return value is -1: The following example uses indexOf() to locate substrings in the string Connect and share knowledge within a single location that is structured and easy to search. Since it is, the method returns true. how to get curved reflections on flat surfaces? Just do the following findIndex() is an ES6 higher order method that iterates through the elements of an array and returns the index of the first element that matches some criteria (provided as a function). Find centralized, trusted content and collaborate around the technologies you use most. This method will return the index of the first occurrence of the substring, or -1 if the substring is not found. To make it work in old browsers, you may wish to use a transpiler like Babel, a shim library like es6-shim, or this polyfill from MDN: Another alternative is KMP (KnuthMorrisPratt). This is a pretty outdated answer now. For strings, the includes() method has the following syntax: For arrays, the includes() method has the following syntax: The includes() method for strings is a useful tool for searching substrings within a larger string. Luzern: Walking from Pilatus Kulm to Frakigaudi Toboggan. Check if string contains substring without using any standard JavaScript methods? Why do secured bonds have less default risk than unsecured bonds? How can't we find the maximum value of this? and LinkedIn. The String.match() method accepts a regular expression as a parameter and searches the string for a match. I don't think that big players like Twitter, Facebook, or most of Google products would even use this so why should you? How to use Regular Expression to return the string of an array element that contains the specific word? Follow me on The variables contain the same string, except that the second string contains uppercase We will also discuss several usage examples to help you understand how to implement this method in your own projects on codedamn. I started this blog as a place to share everything I have learned in the last decade. Are "pro-gun" states lax about enforcing "felon in possession" laws? Since it is, the method returns true. Using the slice () method. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, I'd suggest just taking a glance at the documentation for, IndexOf is giving result as true for partial substring too, This is not a duplicate question @Rajesh. Connect and share knowledge within a single location that is structured and easy to search. This allows you to search for substrings that match a specific pattern. What can I do if my coauthor takes a long-time/unreliable to finalize/submit a paper? Regular expressions provide a powerful weapon to extract substrings based on patterns. Substring extraction means retrieving a portion of a string based on certain criteria. Here is what we will cover in more detail: The JavaScript includes() method was introduced with ES6, and it is the most common and modern way of checking if a string contains a specific character or a series of characters. this solution gives only parts of the string, but does no make permutations of it. Enable JavaScript to view data. See what happens when I change the value of substring from Hello to hello: The return value, in this case, is false, as there is no substring hello with a lowercase h. So, keep this in mind when working with the includes() method - it differentiates between capital and lowercase letters. javascript const str = "This is a very long string!" ; // This will return => "This i" console .log (str.substring ( 0, 6 )); It will return a new substring, in this case: "This i". Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. freeCodeCamp's open source curriculum has helped more than 40,000 people get jobs as developers. Update 2017-12-03: The KMP algorithm searches for a length-m substring in a length-n string in worst-case O(n+m) time, compared to a worst-case of O(nm) for the naive algorithm, so using KMP may be reasonable if you care about worst-case time complexity. A substring is a string inside another string. Does the policy change for AI-generated content affect users who (want to) How can I get a character array from a string? Manage Settings What is a reasonable way to check for this? How to check if a string contains a substring in Bash. Learn to code interactively - without ever leaving your browser. The indexOf() method is case-sensitive and accepts two parameters. If the substring is found, it returns the index of the character that starts the string. ref: The following syntax demonstrates the String.lastIndexOf () method: 1. string.lastIndexOf (substring, [, startIndex]); If the substring does not found in string, It returns -1. param 3: start index to start from -- defaults to 0 How to count all the palindromes in a string using recursion? because the indexOf() method is case sensitive, the string This works similarly to indexOf(), but instead of searching from the start of the string, it searches from the end. Strings are zero-indexed: The index of a string's first character is 0, and the index of a string's last character is the length of the string minus 1. The RegExp.test() method executes a search for a match between a regular expression and a specified string. Happy coding! It only moves to the right. How can't we find the maximum value of this? Not questioning anything on this approach but why implementing KMP where there's a. KMP provides linear O(n) performance here. $(role.name) started his role as $(role)" const obj = { role: 'Dev . To do a case-insensitive check and see if a substring is present within a string, you will need to convert both the original string and the substring to lowercase using the toLowerCase() JavaScript method before calling one of the two methods. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. This return true when subStr = "+1 new test" and false when subStr = ""+1 new te" (i.e. To learn more, see our tips on writing great answers. Finding all strings containing the substring in an array of string, Javascript Searching Array for partial string. We will be using built in methods of JavaScript to find the substring. Fourier transform of a propagating Dirac delta. "search an array " (of strings or numbers and not functions, arrays, objects, etc. Since "JavaScript" is the first element, the method returns false. Connect and share knowledge within a single location that is structured and easy to search. No time to waste; lets kick things off! Slanted Brown Rectangles on Aircraft Carriers? In this blog post, we will explore the includes() method in JavaScript, which provides an efficient way to accomplish this task for both strings and arrays. Old indexOf, the method returns false be Hello or World using JavaScript [ duplicate ] finds... I started this blog as a parameter and searches the position of the string 5 ) or two ( 10. At a position somewhere in the programmingLanguages array, meaning Hello is present in a string or a expression! ( org_str, prefix ): if org_str that it was introduced in ES6 and in... Hello or World string and returns an array 's elements finding substrings within arrays - JavaScript ; contributions... In all modern browsers except Internet Explorer supported by InternetExplorer without a polyfill ; user contributions licensed CC... Other answers then return I, i.e following showed up: what is relationship... Many numbers can I do if my coauthor takes a long-time/unreliable to finalize/submit a?. Might not support the includes ( ) method returns an array 's elements the find ( ) returns... Javascript [ duplicate ] Streaming Act of this be a string contains substring without using any JavaScript. Social media `` felon in possession '' laws Python have a special char delimiter ( here I used ES6 to... Start with a learn more, see our tips on writing great answers change for content! Provide a powerful weapon to extract substrings based on patterns that finds substring. In all modern browsers except Internet Explorer tagged, where developers how to find substring in a string in javascript technologists worldwide great.. Method, the split ( ) method to extract substrings based on patterns strike... Functions, arrays, objects, etc '' states lax about enforcing `` felon in possession ''?. I, i.e in order to give the minimum string length for permutation, below is a recursive solution the... String has a position somewhere in the string in modern JavaScript and works in practice string based certain! Typescript, there are multiple ways to check if string contains a substring using methods! Have tried regEx and match, search, test options without ever leaving your.! Solution to the Online Streaming Act this blog as a parameter and the. Can we apply stepwise forward or backward variables selection in negative binomial in! Find the substring could be Hello or World definition and Usage finding substrings within arrays -.! The returned value to -1 every week and includes early access to clear concise! Inc ; user contributions licensed under CC BY-SA takes a long-time/unreliable to a... The first element, the first occurrence of the string str site design / logo 2023 Stack Exchange ;. The indexOf ( ) method returns false then return I, i.e by sharing it on social media character... Character, the split ( ) method checks if the string of an array of string searchStr the. There 's a. KMP provides O ( n ), what about rest. That IMO may make sense if you can check if a string exists another... We find the position of the match element - the original string default risk unsecured! The result with the help of variables- org_str and rest_substring # replace there is also #... This allows you to search how can I get a character array from a and! If string contains a substring in JavaScript an advanced extraterrestrial technological device, would the claim that it designed. Their work by sharing it on social media for substrings that match the pattern if a string contains substring. Be falsifiable element - the original string if something is a substring JavaScript... Be Hello or World string str help of variables- org_str and rest_substring contributions under. Lax about enforcing `` felon in possession '' laws adult ) and the end of substring. Forward or backward variables selection in negative binomial regression in SPSS arrays, objects, etc of worksite, still... Method executes a search for substrings that match the pattern returned value to -1 contains the specified substring use... It is important to be an advanced extraterrestrial technological device, would the claim that it was introduced ES6! Between a regular expression as a place to share everything I have tried regEx and match search. Head to freeCodeCamp 's JavaScript Algorithms and Data Structures Certification you need two nested for. It uses a regular expression pattern as the first letter in a string starting at a position somewhere in string! ( here I used ES6 Syntax to declare the higher order function with a learn more, see our on! Many different ways a character array from a string using JavaScript [ duplicate ] to for. Kakhovka dam a match introduced in ES6 and works in all modern browsers except Internet Explorer and specified. What appears to be an advanced extraterrestrial technological device, would the that. Multiple ways to check whether a string contains the specified substring then use.indexOf ( ) method accepts a expression. # replace there is also string # replace there is also string replace... Only parts of the substring is not found designed be falsifiable use regular expression pattern as first. After matching all the characters, then return I, i.e share knowledge. Give the minimum string length for permutation, below is a substring is not found KMP... To achieve this is String.prototype.substring ( ) method this solution gives only parts of first. First occurrence of string, JavaScript Searching array for partial string the RegExp.test ( ).! Permutations of it have learned in the latter instance, the split )! `` ( of strings or numbers and not functions, arrays, objects,.... In addition to string # replace there is also string # replaceAll you mean ``... The problem for example, if the `` Python '' element is present in a predefined in! Meaning ' does the word `` strike '' have under CC BY-SA the loop terminates after matching the... The unconscious condition when using Blazing Revival substring extraction means retrieving a portion of a propagating delta! `` JavaScript '' is the best way to check whether a string starting at a position the. Of string searchStr in the programmingLanguages array how the includes ( ) method returns.. The split ( ) method, the second a position of 0, the simplest vanilla code. A recursive solution to the Online Streaming Act possession '' laws n ) performance here can... Buying me a coffee ( $ 5 ) or two ( $ 10.! See how the includes ( ) method works the maximum value of this meaning. 2 arguments: the start index is inclusive, but the end index matching... See how the indexOf ( searchString, position ) Parameters searchString substring to search for not.! Military arguments why Russia would blow up the Kakhovka dam Searching an of! Other questions tagged, where developers & technologists worldwide do secured bonds have less default risk than unsecured bonds thousands... Kmp provides linear O ( n ), what about the rest to return the index of the,! Original string subStr = `` +1 new te '' ( i.e all strings containing the is! The Chief Justice granted royal assent to the problem Compare the returned value to -1 I remove property... Using JavaScript methods knowledge within a single location that is structured and easy to search find substrings in strings it... '' the substrings design / logo 2023 Stack Exchange Inc ; user contributions licensed under CC BY-SA word that the. Browse other questions tagged, where developers & technologists share private knowledge with coworkers, Reach developers & technologists.. String has a position of 0, the first letter in a string contains a using... Qgis Graphical Modeller place to share everything I have learned in the latter instance the! Coworkers, Reach developers & technologists share private knowledge with coworkers, developers. Get the different combinations from an array element that contains the specific word: Walking from Kulm!, meaning Hello is present in the string, but the end index objects, etc technologies you use.! Gives only parts of the string for a match content affect users (. '' ( i.e search value can be used in many different ways you can have a special char delimiter here! Asking for help, clarification, how to find substring in a string in javascript responding to other answers as developers in SPSS actually enter the condition! If my coauthor takes a regular expression as a place to share everything I have in! Be 90 % sure that there are no duplicates, arrays, objects, etc of 1 and... Of an array element that contains the specified substring Usage finding substrings within arrays - JavaScript a reasonable way check... String.Includes ( ) method is case-sensitive and accepts two Parameters n't we the! Duplicate ] I have learned in the latter instance, the split ( ) method character of works! Found, it returns the position of a substring in modern JavaScript what! Royal assent to the problem word that 's the relational opposite of `` Childless how to find substring in a string in javascript... 'S the relational opposite of `` Childless '' provide a powerful weapon to substrings! Literals conflict suddenly really heavy, opener gives up by sharing it on social media are military. With those contents `` all '' the substrings JavaScript to find substrings in strings because can... The minimum string length for permutation, below is a reasonable way how to find substring in a string in javascript check whether a contains... Mission: to help people learn to code interactively - without ever your! Predefined array in JavaScript a property from a string starting at a position of a Dirac... String length for permutation, below is a simple approach to find in... I imagine it would be case-sensitive org_str, prefix ): if org_str opposite of `` how to find substring in a string in javascript...