How to Check Whether a String Contains a Substring in JavaScript?

How to check whether a string contains a substring in JavaScript?
				
					let str = "Hello, world!";
let substr = "world";
console.log(str.includes(substr));  // Output: true

				
			

You can also use the indexOf() method which returns the index of the first occurrence of the substring in the string, or -1 if the substring is not found. Here’s an example:

				
					let str = "Hello, world!";
let substr = "world";
// Output: true
console.log(str.indexOf(substr) !== -1); 

				
			

Or use search method that returns the index of the first match or -1 if not found

				
					let str = "Hello, world!";
let substr = "world";
// Output: true
console.log(str.search(substr) !== -1); 

				
			

Both includes() and indexOf() methods are case sensitive and both are work fine on String objects.

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