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This feature is deprecated in favor of defining getters using the object initializer syntax or the Object.defineProperty()
API. While this feature is widely implemented, it is only described in the ECMAScript specification because of legacy usage. This method should not be used since better alternatives exist.
The __defineGetter__
method binds an object's property to a function to be called when that property is looked up.
Syntax
obj.__defineGetter__(prop, func)
Parameters
prop
- A string containing the name of the property to bind to the given function.
func
- A function to be bound to a lookup of the specified property.
Return value
Description
The __defineGetter__
allows a getter to be defined on a pre-existing object.
Examples
// Non-standard and deprecated way var o = {}; o.__defineGetter__('gimmeFive', function() { return 5; }); console.log(o.gimmeFive); // 5 // Standard-compliant ways // Using the get operator var o = { get gimmeFive() { return 5; } }; console.log(o.gimmeFive); // 5 // Using Object.defineProperty var o = {}; Object.defineProperty(o, 'gimmeFive', { get: function() { return 5; } }); console.log(o.gimmeFive); // 5
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2017 Draft (ECMA-262) The definition of 'Object.prototype.__defineGetter__()' in that specification. |
Draft | Included in the (normative) annex for additional ECMAScript legacy features for Web browsers (note that the specification codifies what is already in implementations). |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | 11 | (Yes) | (Yes) |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | ? | (Yes) | (Yes) |
Compatibility notes
- Starting with Firefox 48 (Firefox 48 / Thunderbird 48 / SeaMonkey 2.45), this method can no longer be called at the global scope without any object. A
TypeError
will be thrown otherwise. Previously, the global object was used in these cases automatically, but this is no longer the case (bug 1253016).
See also
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