JavaScript Advanced (not finished)

Collection array

1. 2 Ways to create arrays

   var fruits = [];
   var friuits = new Array ();

2. Traverse

   Fruits.foreach (function (item, index, array) {
   Console.log (item, index);
   });
   Apple 0
   Banana 1

3. Basic operations

action	code	return value
add element to end of array	fruits.push (' Orange ')	array length
add element To the head of the array	fruits.unshift (' Strawberry ')	array length
delete header element	fruits.shift ();	Header Element
delete trailing elements	fruits.pop ();	trailing element
to find out the index of an element in an array	fruits.indexof (' Banana ');	Subscript
delete an element by index	fruits.splice (index, 1);	deleted elements
copy array	var shallowcopy = Fruits.slice (0,length);	returns a new array of elements within the specified range
generate array	array.from ()	Array.from () method creates a new array instance from a similar array or an iterator object.

1. Example of deleting elements based on an index

   /* Splice (Start:number, Deletecount:number, ... items:t[]): t[]; */

   var fruits = ["Apple", "B", "C", "D"];
   Console.log ("Array is:");
   Fruits.foreach (function (item, index, array) {
   Console.log (item, index);
   });
   var index = fruits.indexof ("B");
   Fruits.splice (index,1);
   Console.log ("Array is:");
   Fruits.foreach (function (item, index, array) {
   Console.log (item, index);
   });

2. Array.from () Use example

   var fruits = ["Apple", "B", "C", "D"];
   var f = array.from (fruits);
   F.foreach (function (item, index, array) {
   Console.log (item, index);
   });
   Apple 0
   B 1
   C 2
   D 3

   var f = array.from ("Hello");
   F.foreach (function (item, index, array) {
   Console.log (item, index);
   });
   H
   E
   L
   L
   O

   Array.from () can also be used for Set,map

Setmap

JavaScript Advanced (not finished)