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This feature is deprecated in favor of defining setters using the object initializer syntax or the Object.defineProperty()
API.
However, as it is widely implemented and used on the Web, it is very unlikely that browsers will stop implementing it.
The __defineSetter__
method binds an object's property to a function to be called when an attempt is made to set that property.
Syntax
obj.__defineSetter__(prop, fun)
Parameters
prop
- A string containing the name of the property to be bound to the given function.
fun
- A function to be called when there is an attempt to set the specified property. This function takes the form
function(val) { . . . }
val
- An alias for the variable that holds the value attempted to be assigned to
prop
.
Return value
Description
The __defineSetter__
method allows a setter to be defined on a pre-existing object.
Examples
// Non-standard and deprecated way var o = {}; o.__defineSetter__('value', function(val) { this.anotherValue = val; }); o.value = 5; console.log(o.value); // undefined console.log(o.anotherValue); // 5 // Standard-compliant ways // Using the set operator var o = { set value(val) { this.anotherValue = val; } }; o.value = 5; console.log(o.value); // undefined console.log(o.anotherValue); // 5 // Using Object.defineProperty var o = {}; Object.defineProperty(o, 'value', { set: function(val) { this.anotherValue = val; } }); o.value = 5; console.log(o.value); // undefined console.log(o.anotherValue); // 5
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript Latest Draft (ECMA-262) The definition of 'Object.prototype.__defineSetter__()' 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
Desktop | Mobile | Server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Basic support | Chrome Full support Yes | Edge Full support Yes | Firefox
Full support
1
| IE Full support 11 | Opera Full support Yes | Safari Full support Yes | WebView Android Full support Yes | Chrome Android Full support Yes | Edge Mobile Full support Yes | Firefox Android Full support 4 | Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android Full support Yes | nodejs Full support Yes |
Legend
- Full support
- Full support
- Deprecated. Not for use in new websites.
- Deprecated. Not for use in new websites.
- See implementation notes.
- See implementation notes.