The method of the array de-weight of JS

Array de-weight? That is, remove duplicate elements from the array ...

First of all, the first method is to use the set set of properties to achieve the de-weight (in fact, a lot of set usage, interested can be more to understand the next);

What is a set set? Set set is a new data storage format;

Set syntax: New set ()

Parameters: An array

The set set can be called the fastest way to de-weight in history, as follows:

var arr = [1, 2, 3, 4, 5, 5, 4, 3, 2, 1 ]; var New set (arr); Console.log (set)

The second method is to encapsulate the good one function to determine if there is a value in the array, and then use this principle to do the array to weight; The code is as follows:

//determine if a value exists in the arrayfunctionhas (arr, n) {varBstop =false;  for(varIincharr) {        if(Arr[i] = =N) {bstop=true;  Break; }    }    returnbstop;}functionNorepeat2 (arr) {varNEWARR = [];  for(varIincharr) {        if(!has (NEWARR, arr[i]))    {Newarr.push (Srr[i])}} returnNEWARR;}

The third method is to use the new method of ES5 to indexof the weight;

IndexOf () function: Determines whether a character exists. Returns the corresponding subscript if it exists, or 1 if it does not exist;

How to achieve it, I believe that the little cutie have thought of the ~ code as follows:

function NOREPEAT3 (arr) {    // Create a new array    var newArr = [];     // looping through arr     for (var in arr) {        // to determine the new array, if it does not exist for ARR, it is added to the new array if none exists        If(Newarr.indexof (arr[i]) = =-1) {            newarr.push (Arr[i])        }    }      return  NEWARR}

The fourth method uses sort sort, creates a new array and then passes to the No. 0 of the original array, and when iterating, note that the initial value of I starts at 1. The code is as follows:

ARRAY.PROTOTYPE.NOREPEART4 =function(){    //Sort First     This. sort (); //create a new array and deposit the No. 0 of the array    varNEWARR = [ This[0]]; //iterate through the incoming array     for(vari = 1;i< This. length;i++){        //take advantage of the value in each new array and the first I of the incoming array, which does not exist then push into the new array        if(Newarr[newarr.length-1]! = This[i]) {Newarr.push ( This[i])}}//returns the new array    returnNEWARR;}

Only unexpectedly not write out! There are a lot of ways to get the array out of the way, so here's a simple list of four. I hope everyone likes (hehe)

The method of the array de-weight of JS