reduce polyfill

before write the code of polyfill, we all should know what are polyfill. I know maximum persons doesn't know the word "Polyfill".

What is polyfill :-

I know you all can read the definition from other sources also. but let's see in 2 lines.

A polyfill is a piece of code (usually JavaScript on the Web) used to provide modern functionality on older browsers that do not natively support it.

TU SMJHA

Koi nhi bro. I am there.

like see that old browsers that doesn't support newer functions like map, reduce, filter (es-6). so we will write code in that way tha every browser can support.

`
//here we will see the implementation of reduce.
//normal using inbuilt reduce function
//syntax
//arr.reduce(callback(accumulator, currentValue), initialValue)

const numbers = [1, 2, 3, 4, 5, 6];
function sum_reducer(accumulator, currentValue) {
return accumulator + currentValue;
}

let sum = numbers.reduce(sum_reducer);
console.log(sum);

let summation = numbers.reduce(
(accumulator, currentValue) => accumulator + currentValue
);
console.log(summation); // 21
`

In this example we are adding the values of array using reduce function. what if browser does not support reduce function. so that's why we will see our own simple implementation.

`
var OwnReduceFun = function(nums, fn, init) {
let ans = init;
for(let el of nums){
ans = fn(ans, el)
}
return ans
};

const numbers = [1, 2, 3, 4, 5, 6];
function sum_reducer(accumulator, currentValue) {
return accumulator + currentValue;
}

//call the function
let ans = OwnReduceFun(numbers, sum_reducer, 0)
console.log(ans) // 21
`

** We create function of reduce named OwnReduceFun that will take nums (Array) fn that is defined already, that will what we want to do and other is initial value**

Now i think all are understood