Javascript if string contains6/19/2023 indexOf ( 'nice', 3 ) != - 1 //false 'a nice string'. There are at least three ways to check: String.indexOf (searchValueString, offsetInteger) returns an index integer or -1 if the string isn't found. indexOf ( 'nice' ) != - 1 //true 'a nice string'. While Klaus is correct that you are working with integers, they arrive at your code as a single string, so it's a valid question. Like includes(), the second parameters sets the starting point: 'a nice string'. In ECMAScript 5 or older environments, use, which returns -1 when a substring cannot be found: var string foo var substring. It returns a boolean value telling presence by true or false. includes () function that helps us to check if a given substring is present inside the string. If the substring is found, it returns the index of the character that starts the string. Use String.includes () to Check if a String Contains Substring in JavaScript ES6 introduced the. Pre-ES6, the common way to check if a string contains a substring was to use indexOf, which is a string method that return -1 if the string does not contain the substring. includes ( 'nice', 2 ) //true Pre-ES6 alternative to includes(): indexOf() includes ( 'nice', 3 ) //false 'a nice string'. includes ( 'nice' ) //true 'a nice string'. Includes() also accepts an optional second parameter, an integer which indicates the position where to start searching for: 'a nice string'. To use it on all browsers, use Polyfill.io or another dedicated polyfill. It’s supported in all modern browsers except Internet Explorer: This method was introduced in ES6/ES2015. The most simple one, and also the canonical one going forward, is using the includes() method on a string: 'a nice string'. JavaScript offers different ways to perform this operation. Learn the canonical way, and also find out all the options you have, using plain JavaScriptĬhecking if a string contains a substring is one of the most common tasks in any programming language. JavaScript offers many ways to check if a string contains a substring. When checking if a specific substring occurs within a string, the correct way to check is test whether the return value is -1: 'Blue Whale'.indexOf('Blue') -1 'Blue Whale'.indexOf('Bloe') -1 Examples Using indexOf () The following example uses indexOf () to locate substrings in the string 'Brave new world'.
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