Jul 10, 2025 · The indexOf() method of Array instances returns the first index at which a given element can be found in the array, or -1 if it is not present.

Description The indexOf() method returns the position of the first occurrence of a value in a string. The indexOf() method returns -1 if the value is not found. The indexOf() method is case sensitive.

Jul 8, 2025 · Learn how to use indexOf () in JavaScript with syntax, examples, best practices, and comparisons with includes (). Perfect for beginners. Tagged with javascript, webdev, beginners, …

In this tutorial, you'll learn how to use the JavaScript String indexOf () method to find the index of a substring within a string.

Sep 30, 2024 · The indexOf () method in JavaScript is used to find the index of the first occurrence of a specified value within a string. The method returns a 0-based index, making it a fundamental …

The indexOf() method starts at a specified index and searches from left to right (from the given start postion to the end of the array). By default the search starts at the first element and ends at the last.

Jul 10, 2025 · 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 …

This tutorial shows you how to use the JavaScript Array indexOf () method to find the first index of the element.

Reports the zero-based index of the first occurrence of the specified string in the current String object. Parameters specify the starting search position in the current string, the number of characters in the …

Dec 20, 2017 · indexOf returns a -1 if the search is not in the string. This is because indexOf will return the position of the search term in the string. For example > -1 is another way of saying !== -1 though …