The task is to validate whether the given string is valid HTML or not using JavaScript. we’re going to discuss a few techniques.
Approach
- Get the HTML string into a variable.
- Create a RegExp which checks for the validation.
- RegExp should follow the rules of creating an HTML document.
Example 1: In this example, a regexp is created and it is validating the HTML string as valid.
html
<h1 style="color:green;" id="h1"> neveropen </h1> <p id="GFG_UP"> </p> <button onclick="GFG_Fun()"> click here </button> <p id="GFG_DOWN"> </p> <script> var up = document.getElementById('GFG_UP'); var str1 = '<div>GeeksForGeeks</div>'; var str = '<div>GeeksForGeeks</div>'; up.innerHTML = "Click on the button to check "+ "for the valid HTML.<br> String - " + str1; var down = document.getElementById('GFG_DOWN'); function GFG_Fun() { down.innerHTML = /<(?=.*? .*?\/ ?>|br|hr|input|!--|wbr)[a-z]+.*?>|<([a-z]+).*?<\/\1>/i.test(str); } </script> |
Output:
How to check if a string is html or not using JavaScript?
Example 2: In this example, Here also, A regexp is created and it is validating the HTML string as invalid.
html
<h1 style="color:green;" id="h1"> neveropen </h1> <p id="GFG_UP"> </p> <button onclick="GFG_Fun()"> click here </button> <p id="GFG_DOWN"> </p> <script> var up = document.getElementById('GFG_UP'); var str1 = '<div>GeeksForGeeks</dv>'; var str = '<div>GeeksForGeeks</dv>'; up.innerHTML = "Click on the button to check "+ "for the valid HTML.<br> String - " + str1; var down = document.getElementById('GFG_DOWN'); function GFG_Fun() { down.innerHTML = /<([A-Za-z][A-Za-z0-9]*)\b[^>]*>(.*?)<\/\1>/.test(str); } </script> |
Output:
How to check if a string is html or not using JavaScript?
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