javascript substring indexof - Brave Search

return a substring using indexOf as a parameter within a function

stackoverflow.com › questions › 36124762 › return-a-substring-using-indexof-as-a-parameter-within-a-function

Use a debugger to find out what you are getting in the userInput. The code is fine. It should work. See sample code below.

test = function() {
    var test = "http://Test 2"
    alert(test.substring(0, test.indexOf("://")))
}

Answer from user883986 on Stack Overflow

developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › String › indexOf

String.prototype.indexOf() - JavaScript | MDN

The indexOf() method of String values searches this string and returns the index of the first occurrence of the specified substring. 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.

stackoverflow.com › questions › 36124762 › return-a-substring-using-indexof-as-a-parameter-within-a-function

javascript - return a substring using indexOf as a parameter within a function - Stack Overflow

Use a debugger to find out what you are getting in the userInput. The code is fine. It should work. See sample code below.

test = function() {
    var test = "http://Test 2"
    alert(test.substring(0, test.indexOf("://")))
}

You need to pass the value to the findProtocol method rather than DOM element

Replace

var userInput = document.getElementById("txtURL");

by

var userInput = document.getElementById("txtURL").value;

and replace

if (URL = true)

with

if( URL == true )

indexOf() in javascript

How does the `indexOf` method on a string work in JavaScript?

javascript - How do I use indexOf to find a substring and then if it finds it set a value to another part of the array?

javascript variable inside indexOf

Writing indexOf function in JavaScript

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w3schools.com › jsref › jsref_indexof.asp

JavaScript String indexOf() Method

The indexOf() method returns the position of the first occurrence of a value in a string.

mimo.org › glossary › javascript › string-indexof-method

JavaScript String indexOf() method: Syntax, Usage, and Examples

The indexOf() method in JavaScript allows you to find the position of a substring within a string. It returns the index of the first occurrence or -1 if the substring doesn’t exist.

geeksforgeeks.org › javascript › javascript-string-indexof-method

JavaScript String indexOf() Method - GeeksforGeeks

The indexOf() method can be used to search for longer substrings: ... // JavaScript to illustrate indexOf() method // Original string let str = 'Departed Train'; // Finding index of occurrence of 'Train' let index = str.indexOf('ed Tr'); ...

Published January 16, 2026

medium.com › @anandgupta20588 › indexof-vs-includes-method-to-search-a-string-character-f48cdf1261ee

indexOf() vs includes() method to search a string/character | by Anandgupta | Medium

November 2, 2023 - ... The indexOf() method is used to find the first occurrence of a specified string within another string. If the substring is found, it returns the index (position) of the first occurrence of the specified value.

elixirforum.com › t › how-to-find-a-substring-position-in-a-string-something-like-indexof-in-js › 68052

How to find a substring position in a string ? something like indexOf in js | Elixir Forum

December 13, 2024 - I have read the docs of String module, it seems that there’s nothing like IndexOf in js which return index of a substring in string. | Elixir Forum

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tutorialspoint.com › javascript › pdf › string_indexof.pdf pdf

JavaScript String indexOf() Method

It can be any · integer between 0 and the length of the string. The default value is 0. Return Value · Returns the index of the found occurrence, otherwise -1 if not found. Example · Try the following example. <html> <head> <title>JavaScript String indexOf() Method</title> </head> <body> ...

geeksforgeeks.org › javascript › how-to-find-the-index-of-specific-character-in-a-string-in-javascript

JavaScript - Index of a Character in String - GeeksforGeeks

July 23, 2025 - It works similarly to indexOf() but searches from the end of the string. JavaScript · let s = "Welcome to GeeksforGeeks"; let c = "G"; let index = s.lastIndexOf(c); console.log(index); Output · 19 · The search() method is a powerful tool used to search for a specific substring within a string.

scaler.com › home › topics › indexof() in javascript

indexOf() in JavaScript- Scaler Topics

July 5, 2022 - The indexOf method in JavaScript is mainly used in string searching operations. The indexOf() method of the String class returns the index of the first occurrence of the substring in a string.

gist.github.com › sashak007 › d19a92207526f72e8cec53bb9c266ffa

JavaScript Implementation of indexOf string · GitHub

Taken from https://stackoverflow.com/questions/46731372/where-should-i-find-how-the-indexof-function-is-written-for-javascript-core-look

educative.io › answers › indexof-method-in-javascript

indexOf() method in JavaScript

In JavaScript, the indexOf() method takes a string and a substring and returns the starting index of the first occurrence of the given substring in that string.

developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › String › substring

String.prototype.substring() - JavaScript | MDN

The index of the first character to include in the returned substring.

forum.freecodecamp.org › curriculum help

Working with Strings in JavaScript - How Can You Find the Position of a Substring in a String? - Curriculum Help - The freeCodeCamp Forum

January 9, 2025 - Tell us what’s happening: Am I missing something, or is there an issue with the following concept check question? The official correct answer is (C), but isn’t (B) correct as well? According to MDN: String.prototype.indexOf() Array.prototype.indexOf() Your browser information: User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:134.0) Gecko/20100101 Firefox/134.0 Challenge Information: Working with Strings in JavaScript - How Can You Find the Position of a Substring in a String?

geeksforgeeks.org › javascript › javascript-program-to-find-the-index-of-the-first-occurrence-of-a-substring-in-a-string

JavaScript Program to find the Index of the First Occurrence of a Substring in a String - GeeksforGeeks

July 23, 2025 - Example: Here is an example to find the index of the first occurrence of a substring in a string using the indexOf() method.

geeksforgeeks.org › javascript › how-to-find-the-index-of-an-element-that-contains-the-given-substring-in-array

How to Find the Index of an Element that Contains the Given Substring in Array ? - GeeksforGeeks

August 5, 2025 - const array = ['apple', 'banana', ... present at index", index); ... Use the findIndex() with indexOf() method to check if the substring exists in any of the element contained by the array....

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developer.mozilla.org › en-US › docs › Web › JavaScript › Reference › Global_Objects › String › lastIndexOf

String.prototype.lastIndexOf() - JavaScript | MDN

The method returns the index of the last occurrence of the specified substring at a position less than or equal to position, which defaults to Infinity. If position is greater than the length of the calling string, the method searches the entire string.

w3schools.com › JAVA › ref_string_indexof.asp

Java String indexOf() Method

charAt() codePointAt() codePointBefore() codePointCount() compareTo() compareToIgnoreCase() concat() contains() contentEquals() copyValueOf() endsWith() equals() equalsIgnoreCase() format() getBytes() getChars() hashCode() indexOf() isEmpty() join() lastIndexOf() length() matches() offsetByCodePoints() regionMatches() replace() replaceAll() replaceFirst() split() startsWith() subSequence() substring() toCharArray() toLowerCase() toString() toUpperCase() trim() valueOf() Java Math Methods ·

webreference.com › javascript › basics › string-methods

JavaScript String Methods Explained

The .indexOf() and .lastIndexOf() methods search for a specified string within another string, and return the index of the first occurrence.