JavaScript-- common object properties and methods of (2)

Array objects (Array)

An array of the most common properties: length Get the number of elements of the array

method:

toString () array into a string

var ARR = [ "Wuhan", "Chengdu", "in the city" ];
 var before = String (ARR); // array into a string 
the console.log (before); // output Wuhan, Chengdu City, Changsha

concat () mosaic array, and returns an array of the stitched

was Arr1 = [1,2,3,4 ];
was arr2 = [888,999 ]; 
Arr1 = arr1.concat (56.78 , arr2); 
console.log (Arr1); // 1,2,3,4,56,78,888,999

join () array broken up into a character string delimited by the development of commonly used ""

var arr = [ "you", "Yes", "my", "best", "Friends" ]; 
arr = arr.join ( ""); // seamless 
console.log (arr); // output that you are my best friend

slice () selected array elements

// Select: Slice obtain an array element or a piece of a certain syntax: .slice array (starting index, the ending subscript + 1'd) 
var idcard = [4,2,0,4,3,4,1,8, 9,4,1,2,2,6,2,0,2,0 ];
 var Print idcard.slice = (10,14 ); // Get birthday 
console.log (print);

splice () to delete an array element, add an array element, the array element replacement

// array of deletions, insertions, substitutions 
@ 1. Delete: Array .splice (subscript started, the number of deleted) 
var ARR = [1,2,3,4 ];
 var arrdelete = arr.splice (0,1 ); // from 0 to delete a 
the console.log (ARR); // result is: [2,3,4] 
@ 2. insert: array .splice (start index, 0, insertion elements) 
var ARR = [11,22,33,44,55 ];
 var arrinsert arr.splice = (0,0,00); // insert 000 will automatically parse the position 0 to 0 on 
the console.log (ARR); // results: [0,11,22,33,44,55] 
@ 3. replace: replace two steps -> delete, insert 
// array .splice (subscript started, the number of deleted, replaced elements ) 
var ARR = [78,88,98,3,4,5,6 ];
 var= arr.splice arrreplace (0,3,0,1,2,10,14); // start the removal of 03 bits and begins at 0, 0,1,2 insert 
the console.log (ARR); // The results are: [0,1,2,3,4,5,6]

shift () Removes and returns the first element of the array

unshift () add an element at the beginning of the array

var ARR = [0,1,2 ]; 
arr.shift (); // delete the array element at the beginning of 
the console.log (ARR); // Output [1,2] 
arr.unshift (0); // at the beginning of the array a plurality of additive elements can be added to 
the console.log (ARR); // output [0,1,2]

pop () Removes and returns the last element of an array

push () is added to the end of the array elements

var bus = [];
for( var i =1;i<=5;i++){
    bus.push("乘客"+i);
}
console.log(String(bus));
while(bus.length>0){
    var last= bus.pop();
    console.log(last+"下车");
    console.log(String(bus));
}

sort () to sort the array elements

var ARR = [1,5,3,6,4,2,20,14 ];
 // Sort () using the default string in ascending order, if required collation has its own, the need to customize the comparator 
arr.sort (); 
the console.log (String (ARR)); 
// custom comparator function 
// comparator functions: compare any two specialized function of the magnitude values 
// 1. define a comparison function that takes two parameters a, b if a> b returns true (descending), otherwise returns false (ASC) 
function CMP (A, B) {
     return B- A; 
} 
arr.sort (CMP); 
the console.log (String (ARR));

reverse () element array reversal

// 2.Reverse () array element responsible reversed 
var ARR = [ 'A', 'B', 'C', 100 ]; 
arr.reverse (); 
the console.log (String (ARR)); // Output [ 100, 'c', 'b ', 'a']

JavaScript-- common object properties and methods of (2)

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