JavaScript cloning a "class" instance

 

This question already has an answer here:

  • How do I correctly clone a JavaScript object? 54 answers

    • $.extend is only cloning plain objects. If the object has a constructor then it is not cloned, but just copied.

    From the $.extend source: 

    if ( jQuery.isPlainObject(copy) /* ... */) {
  // do the recursive $.extend call and clone the object                
} else if ( copy !== undefined ) {
  target[ name ] = copy;
  // ^^^^^ just copy
}

    So $.extend() will call isPlainObject(el) which will return false, because el has an constructor and instead of cloning the el is copied. So states[1].elements[0] is the same object as states[0].elements[0] because it was not cloned.

    If we modify your example from: 

    function Element(){
  this.changes = {};
}
var el = new Element();    // $.isPlainObject(el); <- false
// ...

    into: 

    var el = { changes: {} };  // $.isPlainObject(el); <- true
// ...

    It will clone the el properly. See it HERE .

    您可以使用http://documentcloud.github.com/underscore/#clone克隆对象，如： 

    var cloned = _.clone(states[0]);
    链接地址: http://www.djcxy.com/p/24766.html

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