Object.prototype.__defineGetter__()

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

undefined.

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

Browser compatibility

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

• Object.prototype.__defineSetter__()
• get operator
• Object.defineProperty()
• Object.prototype.__lookupGetter__()
• Object.prototype.__lookupSetter__()
• JS Guide: Defining Getters and Setters
• [Blog Post] Deprecation of __defineGetter__ and __defineSetter__
• bug 647423