Check if a string contains a substring in JavaScript
Today we’ll explain to you how to check if a string contains a substring in JavaScript. It is very simple to do this task in JavaScript.
You can also check the similar articles on String and array" title="Array">Array.
Ways to check if a string contains a substring
1. includes() method
We can use the includes() method to check if a string contains a substring in JavaScript. This method returns the `true` if a substring found in a string otherwise returns `false`.
var str = 'cluemediator';
str.includes('clue');
// Output: true
Note that this is case-sensitive search, so the following example returns `false`.
var str = 'Cluemediator';
str.includes('clue');
// Output: false
Also, in this method we can pass a second parameter that defines which index to start the search. The syntax look like below:
str.includes(substr, 30);
If you know that the first 30 characters do not include a substring then you can use the above method.
2. indexOf() method
The indexOf() method is like the `includes()` method but difference is the `includes()` method returns the boolean value and `indexOf()` method returns the position of the substring starting from the left. It returns `-1` if it is not found.
var str = 'cluemediator';
str.indexOf('mediator');
// Output: 4
This method is also case-sensitive and returns the `0` based index position.
Also, you can pass an optional second parameter to define the index to start the search like below.
var str = 'The string contains the substring';
str.indexOf('string',15);
// Output: 27
3. search method
The search method is similar to the `indexOf()` method that returns the position of the substring. It is a case-insensitive method and its required single parameter as string or regular expression.
var str = 'The string contains the substring';
var reg = /String/i; // i flag for case-insensitive
var pos = str.search(reg);
console.log(pos);
// Output: 4
That’s it for today.
Thank you for reading. Happy Coding..!!
