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What web browsers use the __proto__? Mozilla states that:
Note that
__proto__may not be available in JavaScript versions other than that in Mozilla.
326
The __proto__ getter function exposes the value of the internal [[Prototype]] of an object. For objects created using an object literal, this value is Object. prototype . For objects created using array literals, this value is Array.
prototype is a property of a Function object. It is the prototype of objects constructed by that function. __proto__ is an internal property of an object, pointing to its prototype. Current standards provide an equivalent Object.
In JavaScript, every function and object has a property named prototype by default. For example, function Person () { this.name = 'John', this. age = 23 } const person = new Person(); // checking the prototype value console.
dunder proto === __proto__ Every object in JS has this property. It points back to the prototype object of the constructor function that created that object.
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.
141
The Browser Security Handbook has a table showing which browsers expose __proto__.
Currently, those browsers are:
Those excluded:
31
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;
}
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