Javascript copy array implementation code_Basic knowledge

1. Wrong implementation
Many people may directly use the equal sign to assign values:

Copy the code The code is as follows:

var array1 = new Array("1","2","3");
var array2;
array2 = array1;
array1.length = 0;
alert(array2); //returns empty

This approach is wrong because javascript is divided into primitive types and reference types (similar to java and c#). Array is a reference class
type. array2 gets a reference, so modifications to array1 will affect array2.
2. Use slice()
You can use slice() to copy, because slice() also returns an array.

Copy code The code is as follows:

var array1 = new Array("1","2 ","3");
var array2;
array2 = array1.slice(0);
array1.length = 0;
alert(array2); //Return 1, 2, 3

3. Use concat()
Note that concat() returns not the Array of the calling function, but a new Array, so you can use this to copy.

Copy code The code is as follows:

var array1 = new Array("1","2 ","3");
var array2;
array2 = array1.concat();
array1.length = 0;
alert(array2); //Return 1, 2, 3

4. Test

Copy code The code is as follows:

< ;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

in IE8 Both passed the test under FF3.0 and FF3.0