JavaScript对象克隆

Question

有人能解释一下为什么在这种情况下obj会返回{a:2}而不是{a:1}吗？

var obj = {a:1};
var data = {b:obj};
data.b.a = 2;

console.log(obj); // {a:2}

Answer 1

在这种情况下，您不是在克隆对象，而是设置对同一变量的额外引用。data.obj.a和obj.a指向完全相同的内存位置。第3行将该内存值设置为2。

要执行深度克隆，请尝试执行以下操作：

var data = JSON.parse(JSON.stringify(obj));

Answer 2

如果使用NS派生的浏览器，如FF：

var data = { b: eval ( obj . toSource ( ) ) } ;

或

var data = { b: eval ( uneval ( obj ) ) } ;

如果不是：

Object . function . deepClone = function(){ 
/*
     highly non-trivial to accommodate objects like:
              animal=123; animal.beastly=432;                                        ie. object "overloading"
              monster = new ( function ( ) { this . this = this } ) ( )            ie. self-referential / recursive
      Note: JSON cannot do these  but  toSource () can handle recursive structures
      alert ( new ( function ( ) { this . this = this } ) ( )  . toSource ( )  );
                                                                                                                   ie.    #1={this:#1#}
      alert ( new ( function ( ) { this [ this ] = this } ) ( )  . toSource ( )  );
                                                                                                                   ie.     #1={'[object Object]':#1#}
      alert ( new ( function ( ) { this [ this . toSource ( )  ] = this } ) ( )  . toSource ( )  );
                                                                                                                   ie.     #1={'({})':#1#}
      alert (    (     #1 = { '({})' : #1# }      )   . toSource ( )  );
                                                                                                                   ie.     #1={'({})':#1#}
*/
 }

var data = { b: obj . deepClone ( )  } ;

在文章中发表了很多很多的尝试，希望deepClone也能这么做

The structured clone algorithm - Web developer guide | MDN

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