JS array element addition and deletion method code instance _javascript tips

JS array elements to add and delete has been more puzzled, and finally found the details of the information, the first I tested the 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 
; returns undefined var a = [1,2,3,4,5] If the array is empty; 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 under the test return value is 7, so the return value of this method is unreliable and needs to be used with 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 var a = [1,2,3,4,5] If the array is empty; var B = A.pop (); a:[1,2,3,4] B:5//No need to return the words directly call it

Push: Adds the 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, which is the var a = [1,2,3,4,5] that is composed of the parameter added to the original array; 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,... var a = [1,2,3,4,5] from that location; 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); With Shift A.splice (0,0,-2,-1); var B = a.length; With unshift var B = A.splice (a.length-1,1); With pop A.splice (a.length,0,6,7); var B = a.length; 
With push reverse: The array is reversed to order 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): Sort the array by the specified parameter 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 entries 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 elements of an array into a string, separator as a separator, and the default comma-delimited var a = [1,2,3,4,5]; var B = A.join ("|"); a:[1,2,3,4,5] B:"1|2|3|4|5" gives a way to simulate javastringbuffer strings using arrays:/** * String handler/function StringBuffer () {var arr = new Array; This.appe 
nd = function (str) {arr[arr.length] = str;

}; this.tostring = function () {return Arr.join ("");
Ping append incoming array into a string}; Today, a join is suddenly discovered in the application as a good way to convert an array to a string, so it is encapsulated as an object using:/** * Converts an array to a specific symbol split string/function Arraytostring (arr,separator) {if!separ 
Ator) 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);
 }