Extend Javascript Form object with prototype - Stack Overflow

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Is there any chance to use prototype on a Form object, this is not working:

Form.prototype.myFunc=function()
{
  alert('OK!');
}

On the other hand, String objects are extendable, for example:

String.prototype.trim = function() {
  return this.replace(/^\s\s*/, '').replace(/\s\s*$/, '');
}

Is there any chance to use prototype on a Form object, this is not working:

Form.prototype.myFunc=function()
{
  alert('OK!');
}

On the other hand, String objects are extendable, for example:

String.prototype.trim = function() {
  return this.replace(/^\s\s*/, '').replace(/\s\s*$/, '');
}

• javascript
• forms
• prototype

Share Improve this question Follow asked Jul 11, 2012 at 8:15 user1517081user1517081 96522 gold badges1111 silver badges3030 bronze badges 1

• since there is no Form object - no, it doesn't work. – Otto Allmendinger Commented Jul 11, 2012 at 8:19

Add a ment  | 

2 Answers 2

Sorted by: Reset to default 9

If you means HTMLFormElement, then it should be

HTMLFormElement.prototype.myFunc=function() {
  alert('OK!');
};

There is no specification that requires DOM objects to implement any kind of inheritance, much less prototype inheritance. Having said that, many browsers do but it is not standardised or universally implemented.

You might like to read What’s wrong with extending the DOM.

In browsers that do implement a prototype inheritance scheme for DOM elements, you can try extending HTMLFormElement.prototype using something like:

if (typeof HTMLFormElement == 'object' && 
    typeof HTMLFormElement.prototype == 'object') {

    // extend HTMLFormElement.prototype

}

Note however that the behaviour of host objects is entirely implementation dependant. The above may do anything, including throw errors.

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