_javascript tips for summarizing array methods in JavaScript

JS array elements to add and delete has been more puzzled, today finally found the details of the information, first to give me the test code-^

var arr = new Array ();
Arr[0] = "AAA";
ARR[1] = "BBB";
ARR[2] = "CCC";
alert (arr.length);//3
Arr.pop ();
alert (arr.length);//2
//alert (arr[arr.length-1]);//bbb
Arr.pop ()
; Alert (arr[arr.length-1]);//aaa
//alert (arr.length);//1
 
var arr2 = new Array ()
; alert (arr2.length);//0
arr2[0] = "AAA";
ARR2[1] = "BBB";
alert (arr2.length);//2
Arr2.pop ();
alert (arr2.length);//1
arr2 = Arr2.slice (0,arr2.length-1)
; alert (arr2.length);//0
arr2[0] = "AAA";
ARR2[1] = "BBB";
ARR2[2] = "CCC";
ARR2 = Arr2.slice (0,1);
alert (arr2.length);//1
alert (arr2[0]);//aaa
alert (arr2[1));//undefined

Shift: Deletes the first item of the original array and returns the value of the deleted element, or returns undefined if the array is empty

var a = [1,2,3,4,5];
var B = A.shift (); a:[2,3,4,5]  b:1
 

Unshift: Adds a parameter to the beginning of the original array and returns the length of the array

var a = [1,2,3,4,5];
var B = A.unshift ( -2,-1); a:[-2,-1,1,2,3,4,5]  B:7

Note: The test return value under IE6.0 is always undefined,ff2.0 the test return value is 7, so the return value of this method is unreliable, and it is necessary to use splice instead of this method with the return value.

Pop: Deletes the last item of the original array and returns the value of the deleted element, or returns undefined if the array is empty

var a = [1,2,3,4,5];
var B = A.pop (); a:[1,2,3,4]  b:5//No need to return the words directly call it
 

Push: Adds a parameter to the end of the original array and returns the length of the array

var a = [1,2,3,4,5];
var B = A.push (6,7); a:[1,2,3,4,5,6,7]  B:7
 

Concat: Returns a new array that adds a parameter to the original array.

var a = [1,2,3,4,5];
var B = A.concat (6,7); a:[1,2,3,4,5]  b:[1,2,3,4,5,6,7]
 

Splice (Start,deletecount,val1,val2,...) : Deletes the DeleteCount entry from the start position and inserts the Val1,val2 from that location,...

var a = [1,2,3,4,5];
var B = A.splice (2,2,7,8,9); a:[1,2,7,8,9,5]  b:[3,4]
var b = a.splice (0,1);//Same shift
A.splice (0,0,-2,-1); var b = a.length;//Same unshift
var b = A.splice (a.length-1,1);//same pop
a.splice (a.length,0,6,7); var b = a.length;//Same push
 

Reverse: Reverse-order the array

var a = [1,2,3,4,5];
var B = A.reverse (); a:[5,4,3,2,1]  b:[5,4,3,2,1]
 

Sort (orderfunction): Sorting by specified array of parameters

var a = [1,2,3,4,5];
var B = A.sort (); a:[1,2,3,4,5]  b:[1,2,3,4,5]
 

Slice (Start,end): Returns a new array of items from the original array specifying the start subscript to the end subscript

var a = [1,2,3,4,5];
var B = a.slice (2,5); a:[1,2,3,4,5]  b:[3,4,5]
 

Join (Separator): Sets the element of an array to a string, separator as a delimiter, and omitted by default with a comma as the delimiter

var a = [1,2,3,4,5];
var B = A.join ("|"); a:[1,2,3,4,5]  B: "1|2|3|4|5"
 

Then give an array to simulate the Javastringbuffer processing string method:

 
/**
* String handler
/function
StringBuffer ()
{
var arr = new Array;
This.append = function (str)
{
  arr[arr.length] = str;
 
this.tostring = function ()
{return
  arr.join (""); Ping append incoming array into a string
};

 

Today, a join is suddenly found in applications as a good way to convert an array into a string, so it is encapsulated as an object using:

 
/**
* Converts an array to a specific symbol split String */
function arraytostring (arr,separator)
{
if (!separator) separator = "";//separator null defaults to NULL return
  arr.join (separator);
}
 
/**
* Find array contains string/
function arrayfindstring (arr,string)
{
var str = arr.join ("");
  return Str.indexof (string);

The above mentioned is the entire content of this article, I hope you can enjoy.