实现filter
2020-07-12 本文已影响0人
Time_Notes
漏斗
Array.prototype.filter = function(fn){
let newArr = [];
for(let i=0; i< this.length; i++) {
fn(this[i]) && newArr.push(this[i]);
}
return newArr;
}
Array.prototype._filter=function(callback){
return this.reduce((prev,item,index,arr)=>{
callback(item,index,arr)?prev.push(item):null
return prev
},[])
let val=[1,5,6]._filter(item=>item>2)
console.log(val); //[5, 6]
