JavaScript statement semantics Daquan (4)

1. Var arr1=new Array (2)

var arr2=new Array ()

var arr3=new Array ("A", "B")

var arr4=["A", "B"]

All of the above are declarations of arrays

2. Arrays of various methods--

Length//Lengths

Push (item)//Adds a new element to the end of the array and returns the length of the new array

Unshift (item)//Adds a new element to the beginning of the array and returns the array length

Splice ()

　　

  Arrayobject.splice (index,howmany,item1,....., ItemX)

Arr.splice (1,0, "x")//1 is the index, 0 special code, which represents the addition of instructions, X is the deletion of 0 elements, and with the subsequent "X" added in

var col=arr.splice ("X")

The splice () method deletes 0 or more elements starting at index and replaces the deleted elements with one or more values declared in the argument list. This means that 2 elements are removed from the 2nd element and replaced with an "X".

Pop ()//Remove last element

Shift ()//Remove the first element, the array element is automatically moved forward

Concat ()//Connect multiple arrays to return a new connected array

Slice (start,end)//Returns the part of an array as an array, noting that the element of end is not included, and if End is omitted, all subsequent elements are copied

Reverse ()//array rollover

Sort ()//sorting, inside can also have function, function value is greater than 0 when start element interchange--

Arr.sort (Function (v1, v2) {return v1-v2})

IndexOf ()//returns the position where the parameter appears, starting at 0, and returning when it does not exist-1

Split ()//split the string according to the parameter (all the parameters in the string disappear), make up the array

Join ()//from array to string, use parameters to concatenate each element

JavaScript statement semantics Daquan (4)