Neither function supports regular expressions. Case Insensitive Searchīoth String#includes() and String#indexOf() are case sensitive. The includes() function's syntax is only marginally more concise than indexOf(). In general, if you have any doubt about whether code will run in an environment that supports includes(), you should use indexOf(). If you need to support Internet Explorer, you should instead use the String#indexOf() method, which has been a part of JavaScript since ES1 in 1997. You can also use String#includes() in Node.js >= 4.0.0.Ĭompatibility table from Mozilla Developer Network

You can use String#includes() in all modern browsers except Internet Explorer. The more modern way is the String#includes() function. If you have any questions or anything you can find me on my Twitter, or you can read some of my other articles like Unlimited arguments in a JavaScript function in 2 ways.There's two common ways to check whether a string contains a substring in JavaScript.

The includes() method provides cleaner code, but indexOf() returns information that includes() doesn’t. In the example above we can see the application of both methods. NOTE: includes() is not supported in Internet Explorer.Ĭonsole.log('A substring is close enough') Also, includes() accepts the same two parameters as indexOf(). Instead of returning index, includes() method returns true or false. The includes() method performs a case-sensitive search to determine whether one string may be found within another string, returning true or false as appropriate, according to MDN. Check if JavaScript string contains a substring ES6Īmong other things, ES6 introduced includes() method. This concludes pre-ES6 way of checking if JavaScript String contains substring. That means that there was no occurrence of our string after the index we’ve provided. But, when we used indexOf() with the second parameter that is larger than 8, -1 was returned. This means that the first occurrence of our string is on the 8th index. As we can see from the example above when we used indexOf() without the second parameter indexOf() returned 8.

String includes javascript