Go 6 ways to weigh JavaScript

Array.prototype.unique1 =function(){    varn = [];  for(vari = 0; I < This. length; i++)     {        if(N.indexof ( This[i]) = =-1) n.push ( This[i]); }    returnN;} Array.prototype.unique2=function(){    varn = {},r=[];  for(vari = 0; I < This. length; i++)     {        if(!n[ This[i]]) {n[ This[i]] =true; R.push ( This[i]); }    }    returnR;} Array.prototype.unique3=function(){    varn = [ This[0]];  for(vari = 1; I < This. length; i++)     {        if( This. IndexOf ( This[i]) = = i) N.push ( This[i]); }    returnN;} Array.prototype.unique4=function(){     This. sort (); varre=[ This[0]];  for(vari = 1; I < This. length; i++)    {        if( This[i]!== re[re.length-1]) {Re.push ( This[i]); }    }    returnre;} Array.prototype.unique5=function(){    varSelf = This; var_a = This. Concat (). sort (); _a.sort (function(A, b) {if(A = =b) {            varn =Self.indexof (a); Self.splice (N,1);    }    }); returnSelf ;}; Array.prototype.unique6=function(){    return  This. Reduce (function(P, c) {if(P.indexof (c) < 0) P.push (c); returnp; }, []); };

Performance test: (Running with an array of 10000 random numbers)

Method 1 Used 349ms
Method 2 Used 5ms
Method 3 Used 442ms
Method 4 Used 15ms
Method 5 Used 13MS
Method 6 Used 424ms

So, the best idea to the unique an array is to use a "hash map" to check if an item is repeated.

There is a demo page:http://php.js.cn/down/sample/array.html

Original address: 6 ways to get unique values of a Array in Javascript

Go 6 ways to weigh JavaScript