Several clone methods in Javascript

I. In Javascript, if the cloned object is of the basic type, we can assign a value directly:

1 var sStr = "kingwell"; 2 var cStr = sStr; 3 alert (cStr); // output kingwell4 sStr = "abc"; 5 alert (cStr ); // output kingwell;

When a value is assigned to another variable, when the value of that variable changes, the other value will not be affected.

2. If it is not a basic type, it will be all different:

1 var random r = [,]; 2 var m = random RR; 3 alert (m); // output 1, 2, 34 random r = [,]; 5 alert (m); // The output is 3, 2,; the value is changed because m is only a reference of the branch R. If the value of the branch R changes, then m will change accordingly.

If we want to clone an array, the simplest method is as follows:

1 var branch r = [0, 1, 2, 3]; 2 var m = branch R. slice (0); 3 mirror r = [,]; 4 alert (m); // output,. Although the value in mirror R has changed, however, a new array has been created using the slice method.

We can create a function to clone all objects:

 1 function clone(obj) { 2     var o; 3     if (typeof obj == "object") { 4         if (obj === null) { 5             o = null; 6         } else { 7             if (obj instanceof Array) { 8                 o = []; 9                 for (var i = 0, len = obj.length; i < len; i++) {10                     o.push(clone(obj[i]));11                 }12             } else {13                 o = {};14                 for (var j in obj) {15                     o[j] = clone(obj[j]);16                 }17             }18         }19     } else {20         o = obj;21     }22     return o;23 }

Iii. node cloning:

1 var p = document. getElementsByTagName ("p") [0]; 2 var cP = p. cloneNode (); // clone p Node 3 var cP = p. cloneNode (true); // clone the p node, perform in-depth cloning, and clone the node and its sub-content.