# 数组去重方法速度对比

function createTestArray(){

const testArray=[1,2,3,4,5,'a','b','c','d','e'];

for(let i=0;i<13;i++){

testArray.push(...testArray);

}

testArray.sort((a,b)=>Math.random()>0.5?1:-1);

//console.log(`testArray:\${testArray},length:\${testArray.length}`);

return testArray;

}

const testArray=createTestArray();

function showTime(fun){

const start=new Date();

const result=fun();

return `name:\${fun.name},time:\${new Date()-start},result:\${result.join(',')}`;

}

function removeRepeatBySet(){

return [...new Set(testArray)];

}

function removeRepeatByFilter(){

return testArray.filter((item,index,arr)=>arr.indexOf(item)==index);

}

function removeRepeatByForof(){

const obj={},arr=[],value={};

for(let i of testArray){

if(obj[i]==value){

continue;

}else if(obj[i]!=value){

obj[i]=value;

arr.push(i);

}

}

return arr;

}

function removeRepeatByFor(){

const obj={},arr=[],value={};

for(let i= 0,len=testArray.length;i

const item=testArray[i];

if(obj[item]==value){

continue;

}else if(obj[item]!=value){

obj[item]=value;

arr.push(item);

}

}

return arr;

}

const results=[];

for(var i=0;i<10;i++){

results.push(

showTime(removeRepeatBySet),

showTime(removeRepeatByForof),

showTime(removeRepeatByFilter),

showTime(removeRepeatByFor)

);

}

console.log(JSON.stringify(results.sort(),null,4));

[

"name:removeRepeatByFilter,time:10,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFilter,time:10,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFilter,time:12,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFilter,time:6,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFilter,time:7,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFilter,time:7,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFilter,time:8,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFilter,time:9,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFilter,time:9,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFilter,time:9,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFor,time:2,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFor,time:3,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFor,time:3,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFor,time:3,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFor,time:3,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFor,time:4,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFor,time:4,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFor,time:4,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFor,time:5,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByFor,time:6,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByForof,time:11,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByForof,time:6,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByForof,time:6,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByForof,time:7,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByForof,time:8,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByForof,time:8,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByForof,time:8,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByForof,time:9,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByForof,time:9,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatByForof,time:9,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatBySet,time:10,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatBySet,time:13,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatBySet,time:16,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatBySet,time:6,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatBySet,time:7,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatBySet,time:7,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatBySet,time:8,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatBySet,time:9,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatBySet,time:9,result:3,5,a,b,1,4,c,2,e,d",

"name:removeRepeatBySet,time:9,result:3,5,a,b,1,4,c,2,e,d"

]