Check a String Contains a Substring in JavaScript

 

Options : Use the indexOf() Method

The simplest and fastest way to check whether a string contains a substring or not in JavaScript is the indexOf() method. This method returns the index or position of the first occurrence of substring within the string, otherwise, it returns -1 if no match found. Here is an example:

• <script>

•     // Sample string

•     var str = "The quick brown fox jumps over the lazy dog."

•     // Check if the substring exists inside the string

•     var index = str.indexOf("fox");    

•     if(index !== -1){

•         alert("Substring found!");

•     } else{

•         alert("Substring not found!");

•     }

• </script>

In ES6 you can use the includes() method to check if a contains a substring. This method simply returns true or false instead of the index. Let's check out an example:

• <script>

•     // Sample string

•     var str = "The quick brown fox jumps over the lazy dog."

•     // Check if string contains substring

•     if(str.includes("fox")){

•         alert("Substring found!");

•     } else{

•         alert("Substring not found!");

•     }

• </script>

Check out the tutorial on JavaScript ES6 features to learn about new features introduced in ES6.

Further, you can use the search() method to search a particular piece of text or pattern (using regular expression) inside a string. Like indexOf() method the search() method also returns the index of the first match, and returns -1 if no matches were found.

• <script>

•     // Sample string

•     var str = "Color red looks brighter than color blue."

•     // Search the string for a match

•     var index = str.search(/color/i);  

•     if(index !== -1){

•         alert("Substring found!");

•     } else{

•         alert("Substring not found!");

•     }

• </script>

from : https://www.tutorialrepublic.com/faq/how-to-check-whether-a-string-contains-a-substring-in-javascript.php