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, …

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 …

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 …

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 …

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 …

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 …