JavaScript | exec() Method

Difficulty Level : Easy
Last Updated : 12 Apr, 2021

The exec() Method in JavaScript is used to test for match in a string. If there is a match this method returns the first match else it returns NULL.
Syntax:

RegExpObject.exec(str)

Where str is the string to be searched. This is required field.
Example-1: This example searches for the string “computer” in the original string.

html

<!DOCTYPE html>
<html>
 
<body style="text-align:center">
    <h1 style="color:green">
      GeeksforGeeks
  </h1>
    <h2>exec() Method</h2>
     
<p>
      String: GeeksforGeeks is the
      computer science portal for geeks.
  </p>
 
    <button onclick="geek()">
      Click it!
  </button>
    <p id="app"></p>
 
    <script>
        function geek() {
            var str =
                "GeeksforGeeks is the "+
                "computer science portal for geeks.";
           
            var regex = new RegExp("computer", );
            // match "computer" in string.                      
            var rex = regex.exec(str);
            document.getElementById("app").innerHTML =
                " Found " + rex.length + " match: " + rex;
        }
    </script>
</body>
 
</html>

Output:
Before clicking the button:

After clicking the button:

Example-2: This example searches for the string “rep” in the original string.

html

<!DOCTYPE html>
<html>
 
<body style="text-align:center">
    <h1 style="color:green">
      GeeksforGeeks
  </h1>
    <h2>
      exec() Method
  </h2>
     
<p>
      String: GeeksforGeeks
      is the computer science
      portal for geeks.
  </p>
 
    <button onclick="geek()">
      Click it!
  </button>
    <p id="app"></p>
 
    <script>
        function geek() {
            var str =
                "GeeksforGeeks is the"+
                " computer science "+
                "portal for geeks.";
            var regex = new RegExp("rep");
           
            // Match "rep" in string.
            var rex = regex.exec(str);
            alert(rex);
        }
    </script>
</body>
 
</html>