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    Object.getOwnPropertyDescriptor Redirect 1

    Summary

    The Object.getOwnPropertyDescriptor() method returns a property descriptor for an own property (that is, one directly present on an object, not present by dint of being along an object's prototype chain) of a given object.

    Syntax

    Object.getOwnPropertyDescriptor(obj, prop)

    Parameters

    obj
    The object in which to look for the property.
    prop
    The name of the property whose description is to be retrieved.

    Returns

    A property descriptor of the given property if it exists on the object, undefined otherwise.

    Description

    This method permits examination of the precise description of a property. A property in JavaScript consists of a string-valued name and a property descriptor. Further information about property descriptor types and their attributes can be found in Object.defineProperty().

    A property descriptor is a record with some of the following attributes:

    value
    The value associated with the property (data descriptors only).
    writable
    true if and only if the value associated with the property may be changed (data descriptors only).
    get
    A function which serves as a getter for the property, or undefined if there is no getter (accessor descriptors only).
    set
    A function which serves as a setter for the property, or undefined if there is no setter (accessor descriptors only).
    configurable
    true if and only if the type of this property descriptor may be changed and if the property may be deleted from the corresponding object.
    enumerable
    true if and only if this property shows up during enumeration of the properties on the corresponding object.

    Examples

    var o, d;
    
    o = { get foo() { return 17; } };
    d = Object.getOwnPropertyDescriptor(o, 'foo');
    // d is { configurable: true, enumerable: true, get: /*the getter function*/, set: undefined }
    
    o = { bar: 42 };
    d = Object.getOwnPropertyDescriptor(o, 'bar');
    // d is { configurable: true, enumerable: true, value: 42, writable: true }
    
    o = {};
    Object.defineProperty(o, 'baz', { value: 8675309, writable: false, enumerable: false });
    d = Object.getOwnPropertyDescriptor(o, 'baz');
    // d is { value: 8675309, writable: false, enumerable: false, configurable: false }
    

    Notes

    In ES5, if the first argument to this method is not an object (a primitive), then it will cause a TypeError. In ES6, a non-object first argument will be coerced to an object at first.

    > Object.getOwnPropertyDescriptor("foo", 0)
    TypeError: "foo" is not an object  // ES5 code
    
    > Object.getOwnPropertyDescriptor("foo", 0)
    {configurable:false, enumerable:true, value:"f", writable:false}  // ES6 code
    

    Specifications

    Specification Status Comment
    ECMAScript 5.1 (ECMA-262)
    The definition of 'Object.getOwnPropertyDescriptor' in that specification.
    Standard Initial definition. Implemented in JavaScript 1.8.5.
    ECMAScript 6 (ECMA-262)
    The definition of 'Object.getOwnPropertyDescriptor' in that specification.
    Release Candidate  

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support 5 4.0 (2) 8 12 alpha 5
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support ? ? ? ? ? ?

    Based on Kangax's compat table.

    See also

    Document Tags and Contributors

    Contributors to this page: Sheppy
    Last updated by: Sheppy,