How to check for IP address using regular expression in javascript? - GeeksforGeeks

14 Jan, 2022
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 approach discussed above. 
html
<!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]?)$/.test(addr);            }        </script>    </body></center> </html>
Output: 
Before clicking on the button: 
After clicking on the button: 
Approach 2:  
RegExp: Which split the IP address on :(colon) and check for each element whether they are valid or not(0000-ffff).
Example 2: This example using the approach discussed above. 
html
<!DOCTYPE HTML><html> <head>    <title>        How to check for IP address      using regular expression in javascript?    </title></head><center>     <body style="text-align:center;">        <h1 style="color:green;">         GeeksForGeeks     </h1>        <p id="GFG_UP"           style="font-size: 15px;                  font-weight: bold;">        </p>        <button onclick="GFG_Fun()">            click here        </button>        <p id="GFG_DOWN"           style="font-size: 24px;                  font-weight: bold;                  color: green;">        </p>        <script>            var up = document.getElementById('GFG_UP');            var down = document.getElementById('GFG_DOWN');            var addr = '2001:0db8:0000:0000:0000:ff00:0042:8329';            up.innerHTML =              "Click on the button to validate the IP Address.<br>"            + addr;             function GFG_Fun() {                down.innerHTML =/^[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}\:[a-fA-F0-9]{1, 4}$/.test(addr);            }        </script>    </body></center> </html>
Output: 
Before clicking on the button: 
After clicking on the button: 
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