Javascript class Array (array-like) object

The class array object in JavaScript (Array-like object) refers to objects that look like arrays but are not arrays. The arguments variables and document.getElementsByTagName() return values in JavaScript are typical class array objects.

Class Array attributes

• The class array object has one length property and length The value is a non-negative integer.
• Class array objects do not have methods of array objects. For example: push , and pop other methods.

Class array objects can traverse like arrays, but do not support the methods of array objects.

function test1 () {      for (var i = 0; i < arguments.length;i++) {        Console.log (arguments[i ]);    }     instanceof Array);} Test1 (2, 3);   /* Output 2  3  false  */function  test2 () {      Arguments.push ( 1);} Test2 ();   /* error typeerror:undefined is not a function   */

To convert a class array object to a group

sliceMethod can be used to convert an array of classes (Array-like) objects into an array. You only need to call this object using the slice method on the array prototype.

function Arrayify (a) {      return  Array.prototype.slice.call (a);} function test3 () {      var arrayified = arrayify (arguments);    Arrayified.push (1);    Console.log (arrayified);     instanceof Array);} Test3 (2, 3);   /* Output [2, 3, 1]true   */

can also be used as a simple [].slice.call(a) substitute Array.prototype.slice.call(a) .

sliceMethod can be used to convert an array of classes (Array-like) objects/collections into an array. You simply bind the method to this object. The list function in the following code arguments is a class array object.

1 function list () {2   return Array.prototype.slice.call (arguments); 3 }45var//  [1, 2, 3]

In addition to using   Array.prototype.slice.call ( arguments ) , you can also simply use []. Slice.call (arguments)   instead. In addition, you can use   bind   to simplify the process.

1 var unboundslice = Array.prototype.slice; 2 var slice = Function.prototype.call.bind (unboundslice); 3 4 function list () {5   return Slice (arguments); 6 }78var//  [1, 2, 3]

Instance Code

Array.prototype.slice.apply (Document.queryselectorall ('. Total-con li ')). Map (item) ={          if (Item.classname = = ' Hover1 ')            {this. SortField = Item.getattribute (' SortField ')             this. SortType = Item.getattribute (' sorttype ')            return          }        }) 

Javascript class Array (array-like) object