JS's Array

1. What is an array?

An array object uses a separate variable name to store a series of values. That is, the array can store all values with a variable name, each of which has its own ID, so it is easy to access any value with the variable name.

2. Creating an array

(1) General method:

var mycars=new Array ();
Myarr[0]= "Volvo";
Myarr[1]= "BMW";
Myarr[3]= "Saab";

(2) Concise way:

var mycars=new Array ("Volvo", "BMW", "Saab");

(3) Literally:

var mycars=["Volvo", "BMW", "Saab"];

3. Accessing an array

Access to an element by specifying the array name and index number;

The representation of an array is a contiguous memory address in memory

The array name is actually the first address of the contiguous memory address

4. Properties of the array

(1) Duration: length

Syntax: mycars.length;

Note: Since the index of an array always starts with 0, the upper and lower bounds of an array are: 0 and length-1, respectively. The length of an array is 5, and the upper and lower bounds of the arrays are 0 and 4, respectively. At the same time, the length property of the JavaScript array is variable, which requires special attention.

Two or two-D arrays

1. Statement 1

1 var myarr=new Array ();2for (Var i=0;i<3; i++) {3 Myarr[i]=newArray ();4 For (Var j=0;j<6;j++) {5                 Myarr[i][j]= (i) * (j);6                 document.write (myarr[i][j]+ ' &nbsp; ');7             }8 document.write (' <br/>');9}

Statement 2

1 var myarr=[[1,2,3],[4,5,6]];

JS's Array