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How to check for IP address using regular expression in javascript?
  • Last Updated : 12 Sep, 2019

The task is to validate the IP address both IPv4 as well as IPv6. Here we are going to use RegExp to solve the problem.
Approach 1:

  • RegExp: Which split the IP address on .(dot) and check for each element whether they are valid or not(0-255).

Example 1: This example using the appraoach discussed above.




<!DOCTYPE HTML>
<html>
  
<head>
    <title>
        How to check for IP address 
      using regular expression in javascript?
    </title>
</head>
<center>
  
    <body style="text-align:center;">
        <h1 style="color:green;">  
        GeeksForGeeks  
    </h1>
        <p id="GFG_UP" 
           style="font-size: 15px; 
                  font-weight: bold;">
        </p>
        <button onclick="GFG_Fun()">
            click here
        </button>
        <p id="GFG_DOWN"
           style="font-size: 24px;
                  font-weight: bold;
                  color: green;">
        </p>
        <script>
            var up = document.getElementById('GFG_UP');
            var down = document.getElementById('GFG_DOWN');
            var addr = '172.169.43.1';
            up.innerHTML =
              "Click on the button to validate the IP Address.<br>"
            + addr;
  
            function GFG_Fun() {
                down.innerHTML = 
/^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/.test(addr);
            }
        </script>
    </body>
</center>
  
</html>

Output:

  • Before clicking on the button:
  • After clicking on the button:

Approach 2:

  • RegExp: Which split the IP address on :(colon) and check for each element whether they are valid or not(0000-ffff).

Example 2: This example using the approach discussed above.




<!DOCTYPE HTML>
<html>
  
<head>
    <title>
        How to check for IP address 
      using regular expression in javascript?
    </title>
</head>
<center>
  
    <body style="text-align:center;">
        <h1 style="color:green;">  
        GeeksForGeeks  
    </h1>
        <p id="GFG_UP" 
           style="font-size: 15px; 
                  font-weight: bold;">
        </p>
        <button onclick="GFG_Fun()">
            click here
        </button>
        <p id="GFG_DOWN" 
           style="font-size: 24px;
                  font-weight: bold; 
                  color: green;">
        </p>
        <script>
            var up = document.getElementById('GFG_UP');
            var down = document.getElementById('GFG_DOWN');
            var addr = '2001:0db8:0000:0000:0000:ff00:0042:8329';
            up.innerHTML = 
              "Click on the button to validate the IP Address.<br>" 
            + addr;
  
            function GFG_Fun() {
                down.innerHTML = 
/^[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}$/.test(addr);
            }
        </script>
    </body>
</center>
  
</html>

Output:

  • Before clicking on the button:
  • After clicking on the button:

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