Simple js compose

The concept of compose is simple — it combines n functions. It’s a pipe flowing right-to-left, calling each function with the output of the last one.

Array.prototype.reduceRight = function (...args) {
  const _this = this
  return _this.reverse().reduce(...args)
}

const compose =
  (...args) =>
  x =>
    args.reduceRight((acc, currFn) => {
      return currFn(acc)
    }, x)

const double = x => x * 2
const inc = x => x + 1

const incAndOct = compose(double, double, double, inc)

incAndOct(2) //24

Explanation:

we are passing 2 to incAndOct function. First it will call inc method then the result will be 3 and next it will apply double method on 3 so result is 6 again one more double but this time on double(3) i.e 6 result is 12 now final double on 12 it is 24