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Substring check in JavaScript

  • Last Updated : 14 Mar, 2019

The includes() method can be used to check whether a string contains a specified substring. It returns true if substring is present. This method is case sensitive.

Syntax:

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string.includes(searchvalue, start)

Parameters: This method requires 2 parameters :-

  • searchvalue: Required. It specifies the substring that needs to be searched.
  • start: Optional. It specifies the index from where the searching is performed. By default it is 0.

Return Value: True if the specified substring is present in string else returns false.

Example:




<!DOCTYPE html>
<html>
    <body>
        <h1>Welcome to GeeksforGeeks</h1>
        <p>Click the button to check whether 
            <b>Geeks</b> is present in the below string.
        </p>
        Hello there! Welcome to GeeksforGeeks.<br><br>
        <button onclick="myFunction()">Try it</button>
        <p id="display"></p>
  
        <!--script to check string contains the specified substring.-->
        <script>
            function myFunction() {
              var str = "Hello there! Welcome to GeeksforGeeks.";
                 
              var flag = str.includes("Geeks");
              document.getElementById("display").innerHTML = flag;
            }
        </script>
    </body>
</html>

Output:
Before clicking try it button:

After clicking try it button:

Supported Browsers: The browser supported by includes() Method are listed below:

  • Google Chrome 41
  • Apple Safari 9
  • Firefox 40
  • Opera 28
  • Edge 12.0
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