Summary of calling methods for javascript arrays_javascript skills

JS array method summary
shift: delete the first item of the original array and return the value of the deleted element; if the array is empty, it returns undefined
var a = [1,2,3,4,5] ;
var b = a.shift(); //a: [2,3,4,5] b: 1

unshift: Add parameters to the beginning of the original array and return 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, and the test return value under FF2.0 is 7, so the return value of this method is unreliable. When you need to use the return value Splice can be used instead of this method.

pop: Delete the last item of the original array and return the value of the deleted element; if the array is empty, it returns undefined
var a = [1,2,3,4,5];
var b = a.pop(); //a: [1,2,3,4] b: 5

push: Add parameters to the end of the original array and return 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 formed by adding parameters 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,...): Delete the deleteCount item from the start position and insert val1, val2,...
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 as shift
a.splice(0,0,-2,-1); var b = a.length; //Same as unshift
var b = a. splice(a.length-1,1); //Same as pop
a.splice(a.length,0,6,7); var b = a.length; //Same as push

reverse: Reverse 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): Sort the array according to the specified 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 composed of items between the specified start index and the end index in the original array
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): Group the elements of the array into one String, with separator as the separator, if omitted, the default comma is used as the separator
var a = [1,2,3,4,5];
var b = a.join("|" ); //a：[1,2,3,4,5] b："1|2|3|4|5"