数组函数

function map(arr,iteratee){
  for(var i=0;i<arr.length;i++){
    arr[i] = iteratee(arr[i],i,arr)
  } 
  
}
var arr1 = [1,2,'haha',4]
map(arr1,function(val,ind,arr){
  return val + val
})
//console.log(arr1)

function find(arr,predicate){
  for(var i =0;i<arr.length;i++){
    if(predicate(arr[i])){
      //console.log(arr[i])
      return  [arr[i],i]
      break;
     
      
    }
      
  }
}

var ev = find([10,1,2,4,67,8],function(num){
  return num % 2 === 0
})

//console.log(ev)

function fitlter(list,predicate){
  var arr = []
  for(var i =0;i<list.length;i++){
    if(predicate(list[i],i,list)){
      arr.push(list[i])  
    }
  }
  return arr
}

var haha = fitlter([1,3,45,4,6,82],function(num,index,arr){
  return num % 2 ===0
})
console.log(haha)