Polyfills

Polyfills.js

// map
Array.prototype.myMap = function (cb) {
  const results = [];
  for (let i = 0; i < this.length; i++) {
    results[i] = cb(this[i], i, this);
  }
  return results;
};

// filter
Array.prototype.myFilter = function (cb) {
  const results = [];
  for (let i = 0; i < this.length; i++) {
    const isTrue = cb(this[i], i, this);
    if (isTrue) {
      results.push(this[i]);
    }
  }
  return results;
};

// reduce 
Array.prototype.myReduce = function (cb, iv) {
  let acc = iv || undefined;
  for (let i = 0; i < this.length; i++) {
    if (acc) {
      acc = cb(acc, this[i], i, this);
    } else {
      acc = this[i];
    }
  }
  return acc;
};

// call
Function.prototype.myCall = function (context, ...args) {
  const currentContext = context || window || globalThis;
  currentContext.fn = this;
  const res = currentContext.fn(...args);
  delete currentContext.fn;
  return res;
};

// apply 
Function.prototype.myApply = function (context, args) {
  const currentContext = context || window || globalThis;
  currentContext.fn = this;
  const res = currentContext.fn(args);
  delete currentContext.fn;
  return res;
};

// bind
Function.prototype.myBind = function (context, ...args) {
    const currentContext = context || window || globalThis;
    const _this = this;
    return function (..a) {
        _this.call(currentContext, ...[...args, ...a] );
    }
};