How to copy/clone a hash/object in JQuery?

问题

I have a simple object (or hash) in Javascript:

var settings = {
  link: 'http://example.com',
  photo: 'http://photos.com/me.jpg'
};

I need a copy of it. Is there a settings.clone() type method that will give me another object with the same attributes? I'm using jQuery, so happy to use a jQuery utility method if one exists.

回答1:

Yes, extend an empty object with the original one; that way, everything will simply be copied:

var clone = $.extend({}, settings);

Extending some filled object with another, e.g.:

$.extend({a:1}, {b:2})

will return:

{a:1, b:2}

With the same logic:

$.extend({}, {foo:'bar', test:123})

will return:

{foo:'bar', test:123}

i.e. effectively a clone.

回答2:

In a non jQuery way.

var newObj = {};

Object.keys(settings).forEach(function(key) {
     newObj[ key ] = settings[ key ];
});

This copies only the top-level properties. To copy hashes with nested objects as property values, you will need to use a recursive function.

NB: The Object.keys(settings) avoids the need for calling settings.hasOwnProperty(key).

回答3:

var clone = $.extend(true, {}, settings);

Set first argument to true.

EDIT: First argument true signifies deep copy. For given example in original question there is no need for deep copy since there are simple immutable key-value pairs. For question in title - as a general case - use deep copy. Otherwise you get half-copy.

回答4:

It sounds like you want jQuery extend, which can copy an object for you.

http://api.jquery.com/jQuery.extend/

回答5:

Underscore.js also has an extend function if you are not using jQuery:

extend _.extend(destination, *sources) Copy all of the properties in the source objects over to the destination object, and return the destination object. It's in-order, so the last source will override properties of the same name in previous arguments.
_.extend({name: 'moe'}, {age: 50});
=> {name: 'moe', age: 50}

回答6:

My 2 cents:

function clone(hash) {
  var json = JSON.stringify(hash);
  var object = JSON.parse(json);

  return object;
}

It may not be the most optimized option but it can be handy for some scenarios.

来源：https://stackoverflow.com/questions/7113865/how-to-copy-clone-a-hash-object-in-jquery

标签

javascript

jquery

copy

clone

javascript-objects