Detailed explanation of HTML array_html/css_WEB-ITnose

Array

1. Array declaration:

1. One-dimensional array

var x=new Array();//Empty array

var x = new Array(size); //Array of specified length

var x = new Array(element 0,element 1,...); //Specify initial value,,,, does not limit the data type stored

Also: var x =["Xiao Ming", "Xiao Hong"];//Indicates one-dimensional array array elements----Xiao Ming, Xiao Hong

3] means that the length of the array x is 3; = {'you', 'good', 'ah'};

arr[1] = {'you', 'true', 'beautiful'};

arr[2] = {'you' , 'are' , 'full'};

//Traverse the two-dimensional array

for(var i=0; i

{

for(var j=0; i

Document.write(arr[i] [j] ” ”);

}

Document.write('

---

');

}

2. The length and subscript of the array

1. var a = new Array(); define a null pointer

But a subscript that exceeds the length of the array means changing the length of the array

2. a.length=5 (adding numbers directly changes the length------can be lengthened or shortened)

But alert (a[6]) will display undefined

3. Commonly used methods for arrays

Methods

Function

document.write(arr.slice(2,-2));

EG	concat	Concatenates two or more arrays and returns the result
var c=a.concat(b);	Join	Convert all elements of the array Put a character into the element
Var a=new Array(''a,'b'); a.join('"!")	pop	Remove and return the last element of the array
a.pop();	Push	Adds one or more elements to the end of the array and returns the new length
Returns the length	Reverse	Reverse the order in the array
Return new array after inversion	Shift	Delete and return array The first element of
removes and returns the removed element	Slice	Return selected elements from an existing array
var arr = ["George","John","Thomas","James" ,"Adrew","Martin"];	//Thomas,James//Negative numbers count from the back to -2 (i.e. the third to last number)	Sort() Sort the elements of the array
The default is to sort according to the order of character encoding Parameter writing comparison function		splice Delete elements and add new elements to the array
1. splice(index deleted position Negative numbers count backwards, howmany quantity, new1, add from deleted position, new2...)		tostring Convert the array to a string and return the result
is designed for strings and automatically adds , number	Unshift	Adds one or more elements to the beginning of the array and returns the new length