JS array array detailed explanation_basic knowledge

1. Array declaration method
(1): arrayObj = new Array(); //Create an array.

Copy code The code is as follows:

var arr1 = new Array();

(2): arrayObj = new Array([size]) Create an array and specify the length. Note that it is not the upper limit, but the length.

Copy code The code is as follows:

var a = new Array(5);

(3): arrayObj = new Array([element0[, element1[, ...[, elementN]]]]) Create an array and assign values.

Copy code The code is as follows:

var a = new Array(["b", 2 , "a", 4,]);

(4): arrayObj = [element0, element1, ..., elementN] is the abbreviation for creating an array and assigning values. Note that the square brackets do not indicate Can be omitted.

Copy code The code is as follows:

var a = ["b", 2, "a ", 4,];

(Note): Pay attention to the difference between "[]" and without "[]"

Copy Code The code is as follows:

var a = new Array(5); //Refers to creating an array of length 5
var a = new Array([ 5]); //Refers to creating an array with a length of 1 and the first digit is 5

2. Common methods of arrays
3. Array operations (passing address)

Copy code The code is as follows:

var t2=new Array();
t2[0 ]=1;
t2[1]=2;
test2(t2); //Pass address (array)

function test2(var2) {
for(var i=0 ;ivar2[i]=var2[i] 1;
}
}
for(var i=0;ialert(t2[i]);
}