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JavaScript | RegExp constructor

  • Last Updated : 30 Sep, 2021

The RegExp constructor in JavaScript is used to return the function that created the RegExp object’s prototype i.e. the construction function for an object. It returns the different reference for various JavaScript types: 
 

  • Regular Expression: The constructor property returns function RegExp() { [native code] } for regular expressions.
  • Numbers: The constructor property returns function Number() { [native code] } for JavaScript numbers.
  • Strings: The constructor property returns function String() { [native code] } for JavaScript strings.

Syntax: 
 

RegExpObject.constructor

Example-1: This example returns the type of constructor on variable regex4. 
 

html




<!DOCTYPE html>
<html>
 
<body style="text-align:center">
    <h1 style="color:green">
      GeeksforGeeks
  </h1>
    <h2>
      RegExp Constructor
  </h2>
     
<p>
      String: ee@128GeeeeK
  </p>
 
    <button onclick="geek()">
      Click it!
  </button>
    <p id="app"></p>
 
    <script>
        function geek() {
            var str1 = "ee@128GeeeeK";
            var regex4 = new RegExp("e{2, }", "gi");
            var rex = regex4.constructor;
            document.getElementById("app").innerHTML =
                " Constructor: " + rex;
        }
    </script>
</body>
 
</html>

Output: 
Before clicking the button: 
 

constructor

After clicking the button: 
 

constructor

Example-2: This example returns the type of constructor on variable match4. 
 

html




<!DOCTYPE html>
<html>
 
<body style="text-align:center">
    <h1 style="color:green">
      GeeksforGeeks
  </h1>
    <h2>
      RegExp Constructor
  </h2>
     
<p>
      String: GeeeeK@128
  </p>
 
    <button onclick="geek()">
      Click it!
  </button>
    <p id="app"></p>
 
    <script>
        function geek() {
            var str1 = "GeeeeK@128";
            var regex4 = new RegExp("e{2, }", "gi");
            var replace = "$";
            var match4 = str1.replace(regex4, replace);
            var rx = match4.constructor;
            document.getElementById("app").innerHTML =
                " Constructor: " + rx;
        }
    </script>
</body>
 
</html>

Output: 
Before clicking the button: 
 

constructor

After clicking the button: 
 

constructor

Supported Browsers: The browsers supported by RegExp constructor are listed below: 
 

  • Google Chrome 1 and above
  • Edge 12 and above
  • Firefox 1 and above
  • Internet Explorer 4 and above
  • Opera 5 and above
  • Safari 1 and above
     

 

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