Three methods for copying arrays using JavaScript

Hey hey, someone recently asked: the fastest way to copy an array. Today I will tell you three methods based on the speed: you may already know

Hey, someone recently asked: the fastest way to copy an array. Today I will tell you three methods based on the speed: you may already know!

1. slice ();

(Function (){

Var abc = ["abc", "cad"];

Var cab;

Cab = abc. slice ();

Abc [0] = "ccc ";

Alert (cab );
Alert (abc );

})();

Because slice is a built-in method, it is the fastest.

2. concat ();

(Function (){

Var abc = ["abc", "cad"];

Var cab;

Cab = []. concat (abc );

Abc [0] = "ccc ";

Alert (cab );
Alert (abc );

})();

3. for... in

(Function (){

Var abc = ["abc", "cad"];

Var cab = [];

For (var k in abc ){

Cab [k] = abc [k];

}

Abc [0] = "ccc ";

Alert (cab );
Alert (abc );

})();

2 Responses to "three methods for copying arrays"

1. Jade said: September 22, 2011

   Var s = + new Date; var a = ['1', '2', '3']; var len =. length; for (I = 0; I <10000; I ++) var B =. splice (0, len); e = + new Date; alert (e-s); // 32 is indeed the fastest

   Three other methods:

   Var s = + new Date; var a = ['1', '2', '3']; for (I = 0; I <10000; I ++) var B =. join (','). split (','); e = + new Date; alert (e-s); // around 45, slightly slower

   Var s = + new Date; var a = ['1', '2', '3']; for (I = 0; I <10000; I ++) var B = JSON. parse (JSON. stringify (a); e = + new Date; alert (e-s); // 68 the parsing of this involved object is created

   Var s = + new Date; var a = ['1', '2', '3']; var len =. length; for (I = 0; I <10000; I ++) var B =. splice (0, len); e = + new Date; alert (e-s); // 34 this method is similar to slice