Property name	describe
prototype	Adding attributes and methods to objects
constructor	Returns an array object reference
length	Returns the number of array elements

Method name	describe	Return	Change the original array
concat()	Connect multiple arrays	New array after connection	N
join('')	Combines all elements in an array into a string. Delimitation by delimiter	New array after merging	N
toString()	Converting an array to a string (the same as a nonparametric join, comma join)	Converted string	N
pop()	Delete the last element of the array (top of the stack)	Deleted element values	Y
push()	Add one/more elements to the end of the array	New array length	Y
shift()	Delete the first element of the array	Deleted element values	Y
unshift()	Add one/more elements to the beginning of an array	New array length	Y
reverse()	Reverse the order of elements in an array	Post-inverted array	Y
slice(start,end)	Intercept subarrays from start to end (end is omitted at the end of the array)	Intercept subarray	N
splice()	(start,length,item1,item2,...) Delete elements and add new elements	Delete subarrays	Y
sort()	Sort the elements of an array (self-defining rules)	Post-sorted arrays	Y
valueOf()	Returns the original value of the Array object	Array object	N

Create Array objects

new Array();
new Array(size);
new Array(element0, element1, ..., elementn);
var arr = []; //Literary Quantity

It takes about the same amount of time as new Array() in the literal way. The difference in usage habits is that ~ new Array() can initialize the length.~

attribute

prototype adds attributes and methods to objects

function em(A,B)
{
    this.A = A;
    this.B = B;
}
var e = new em("AA","BB");
em.prototype.C = null;
e.C = 20000;
console.log(e.C); //20000
console.log(e); //em {A:"AA" , B:"BB" , C : 20000 }

constructor returns a reference to the array function that created this object

function employee(name,job)
{
    this.name = name;
    this.job = job;
}
var bill = new employee("Bill");
console.log(typeof bill.constructor); // function
console.log(bill.constructor); //function employee(name){this.name=name;this.job=job;}

Method

concat() connects two or more arrays (returns a copy of the connected array)

var arr = [1, 2, 3];
var arr1 = [6, 7];
console.log(arr.concat(4, 5, arr1)); //[1, 2, 3, 4, 5, 6, 7]

join() puts all elements of an array into a string, separated by a specified delimiter.

var arr = ['item 1', 'item 2', 'item 3'];
var list = '<ul><li>' + arr.join('</li><li>') + '</li></ul>'; //'<ul><li>item 1</li><li>item 2</li><li>item 3</li></ul>'

toString() array is converted to a string (the same as the string returned by the nonparametric join() method)

var arr = new Array(3)
arr[0] = "A"
arr[1] = "B"
arr[2] = "C"
console.log(arr.toString()); //"A,B,C"

pop() deletes the last element of the array, decreases the length of the array by 1, and returns the value of the deleted element

If the array is empty, pop() returns undefined value

var arr = ["A", "B", "C"];
console.log(arr); //["A", "B", "C"]
console.log(arr.pop()); //"C"
console.log(arr); //["A", "B"]

push() adds one or more elements to the end of the array and returns a new length

var arr = ["A", "B", "C"];
console.log(arr); //["A", "B", "C"]
console.log(arr.push('D')); //4
console.log(arr); ////["A", "B", "C" , "D"]

reverse() reverses the order of elements in an array

var arr = ["A", "B", "C"];
arr.reverse();
console.log(arr);// ["C", "B", "A"]

slice(start,end) returns the selected subarray from the array

var arr = ["A", "B", "C"];
// From the first element to the end of the array
console.log(arr.slice(1)); //["B", "C"]
console.log(arr); //["A", "B", "C"]

splice() deletes elements and adds new elements to the array
(Operating directly on arrays)

(1) Delete the array elements of the specified range:

var arr = new Array(6);
    arr[0] = "A"; 
    arr[1] = "B";
    arr[2] = "C";
    arr[3] = "D";
    arr[4] = "E";
    arr[5] = "F";
console.log(arr); //["A", "B", "C", "D", "E", "F"]
// Three array elements after deleting the third element (including the third element)
console.log(arr.splice(2, 3));  //["C", "D", "E"]
console.log(arr); //["A", "B", "F"]

(2) Insert the specified element from the specified subscript (the number of elements is unlimited):

    var arr = new Array(6);
    arr[0] = "A"; 
    arr[1] = "B";
    arr[2] = "C";
    arr[3] = "D";
    arr[4] = "E";
    arr[5] = "F";
console.log(arr); //["A", "B", "C", "D", "E", "F"]
console.log(arr.splice(2, 0, "AA","BB")); // []
console.log(arr);//["A", "B", "AA" , "BB" , "C", "D", "E", "F"]

(3) Delete the array elements of the specified range and replace them with the specified elements (the number of elements is unlimited):

var arr = new Array(6);
    arr[0] = "A"; 
    arr[1] = "B";
    arr[2] = "C";
    arr[3] = "D";
    arr[4] = "E";
    arr[5] = "F";
console.log(arr);//["A", "B", "C", "D", "E", "F"]
console.log(arr.splice(2, 1, "AA","BB")); // ["C"]
console.log(arr); //["A", "B", "AA", "BB", "D", "E", "F"]

sort() sorts the elements of an array
Reference to arrays

Arrays are sorted on the original array and no replicas are generated. By default, this method is sorted in the order of character encoding (ASCII).

var arr = new Array(3);
    arr[0] = "D";
    arr[1] = "S";
    arr[2] = "A";
console.log(arr); //["D", "S", "A"]
console.log(arr.sort()); //["A", "D", "S"]

Specify your own sort rules. As follows:

var arr = new Array(6);
    arr[0] = 10;
    arr[1] = 5;
    arr[2] = 40;
    arr[3] = 25;
    arr[4] = 1000;
    arr[5] = 1;
console.log(arr); //[10, 5, 40, 25, 1000, 1]
//Ascending order
console.log(arr.sort(function (a, b) {return a - b;}));// [1, 5, 10, 25, 40, 1000]

valueOf() returns the corresponding original value

var arr = new Array(2);
    arr[0] = 10
    arr[1] = 5
console.log(arr); //[10, 5]
console.log(typeof arr.valueOf()); //object
console.log(arr.valueOf()); //[10, 5]

shift() deletes and returns the first element of the array

var arr = ["A", "B", "C"];
console.log(arr); //["A", "B", "C"]
console.log(arr.shift()); //A
console.log(arr); //["B", "C"]

unshift() adds one or more elements to the beginning of an array and returns a new length

var arr = ["A", "B", "C"];
console.log(arr); //["A", "B", "C"]
console.log(arr.unshift("AA")); //4
console.log(arr);//["AA", "A", "B", "C"]