Polyfills of Sum,Filter,Map,Reduce

Demo.js

let a2=[1,2,3,4]
//SUM
Array.prototype.sum2 = function () {
let sum = 0

for(let i = 0;i<this.length;i++)
{
  sum+=this[i]
}
return sum

}
console.log(a2.sum2())


//FILTER
Array.prototype.filterArray = function(callback) {
let filterValue = []
for(var i = 0;i<this.length;i++)
{
  if(callback(this[i]))
  filterValue.push(this[i])
}
return filterValue

}
console.log(a2.filterArray(a => a>2))


//MAP
Array.prototype.myMap = function(callback) {
let filterValue = []
for(var i = 0;i<this.length;i++)
{
  filterValue.push(callback(this[i]))
}
return filterValue

}
console.log(a2.myMap(a => a*2))




//REDUCE
Array.prototype.myReduce = function(callback,intialValue=0) {
let acc = intialValue
for(var i = 0;i<this.length;i++)
{
  acc=callback(acc,this[i])  
}
return acc
}
console.log(a2.myReduce((a,c) => a+c))