forEach与filter功能的实现

//forEach的实现
Array.prototype.myForEach = function (fn){

  if((typeof fn).toLowerCase() != 'function'){
    throw new TypeError('must be function')
  }
  let i 
  for(i = 0; i < this.length; i++){
      fn(this[i],i,this)
  }
}  

const arr = [1,4,5]
arr.myForEach((item,index,arr)=>{

console.log(item,index,arr)

})

//filter的实现
Array.prototype.myFilter = function (fn) {

  if( (typeof fn).toLowerCase() != "function"  ){
    throw new TypeError('must be function')
  }
  var arr = this
      arrs =  []
  for(var i = 0; i < arr.length; i++){
    var val = arr[i]
    if(fn.call(null , val,i,arr)){
      arrs.push(val)
    }
  }
  return arrs
}

var arr = [1,2,3,4,5,6]
const as = arr.myFilter((item,index,arr)=>{

return item>2

})
console.log(as)