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Question

JavaScript and __proto__ - what browsers use it?

Answer 1

A:

The end of the sentence you posted is See below for workarounds., where there is a discussion on an alternative method extends() that uses super.prototype:

function extend(child, super){  
  for (var property in super.prototype) {  
    if (typeof child.prototype[property] == "undefined")  
      child.prototype[property] = super.prototype[property];  
  }  
  return child;  
}

Oded 2010-06-21 07:37:12

I know, but I want to know what web browsers are supporting `__proto__`. Depending on the answer, I may not even need that kind of functionality.

rFactor 2010-06-21 07:40:55

Answer 2

+2 A:

The Browser Security Handbook has a table showing which browsers expose __proto__.

Currently, those browsers are:

Firefox 2
Firefox 3
Safari
Chrome
Android

Those excluded:

IE 6, 7, 8
Opera

strager 2010-06-21 07:46:14

Answer 3

+3 A:

Click here for your answer.

Details

The most general way would be to test this page in different browsers:

<html>
  <head>
    <script type="text/javascript">
      function a() {}
      if ( (new a).__proto__ === a.prototype )
          alert('supported');
    </script>

  </head>
</html>

It alerts if a browser supports __proto__. I've submitted it to browsershots.org, which will create screenshots of the page in many different browsers. Thus, you should see--by means of the alert message--which browser does support it.

artistoex 2010-06-21 08:06:58

Thank you! To sum up, it does not work on IE, Safari < 5 and Opera < 10.50.

rFactor 2010-06-21 09:25:52

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JavaScript and proto - what browsers use it?

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