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 |
---|
ECMAScript (ECMA-262) The definition of 'Object.prototype.__defineSetter__()' in that specification. |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
__defineSetter__ | Chrome Full support 1 | Edge Full support 12 | Firefox
Full support
1
| IE Full support 11 | Opera Full support 9.5 | Safari Full support 3 | WebView Android Full support 1 | Chrome Android Full support 18 | Firefox Android Full support 4 | Opera Android Full support 10.1 | Safari iOS Full support 1 | Samsung Internet Android Full support 1.0 | 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.