Function.prototype.bind()

const module = {
  x: 42,
  getX: function () {
    return this.x;
  },
};

const unboundGetX = module.getX;
console.log(unboundGetX()); // The function gets invoked at the global scope
// Expected output: undefined

const boundGetX = unboundGetX.bind(module);
console.log(boundGetX());
// Expected output: 42

    func.bind(thisArg[, arg1[, arg2[, ...]]])

this.x = 9;
var module = {
  x: 81,
  getX: function () {
    return this.x;
  },
};

module.getX(); // 81

var retrieveX = module.getX;
retrieveX();
// 9  -    

// module  'this'    
//     x
// module  x   
var boundGetX = retrieveX.bind(module);
boundGetX(); // 81

function list() {
  return Array.prototype.slice.call(arguments);
}

var list1 = list(1, 2, 3); // [1, 2, 3]

//     .
var leadingThirtysevenList = list.bind(null, 37);

var list2 = leadingThirtysevenList(); // [37]

var list3 = leadingThirtysevenList(1, 2, 3); // [37, 1, 2, 3]

function addArguments(arg1, arg2) {
  return arg1 + arg2;
}

var result1 = addArguments(1, 2); // 3

//      .
var addThirtySeven = addArguments.bind(null, 37);

var result2 = addThirtySeven(5); // 37 + 5 = 42

//    .
var result3 = addThirtySeven(5, 10); // 37 + 5 = 42

function LateBloomer() {
  this.petalCount = Math.ceil(Math.random() * 12) + 1;
}

// 1   bloom 
LateBloomer.prototype.bloom = function () {
  window.setTimeout(this.declare.bind(this), 1000);
};

LateBloomer.prototype.declare = function () {
  console.log("I am a beautiful flower with " + this.petalCount + " petals!");
};

var flower = new LateBloomer();
flower.bloom();
// 1 , 'declare'  

function Point(x, y) {
  this.x = x;
  this.y = y;
}

Point.prototype.toString = function () {
  return this.x + "," + this.y;
};

var p = new Point(1, 2);
p.toString(); // '1,2'

//    ,

//  bind  :

var YAxisPoint = Point.bind(null, 0 /*x*/);

var emptyObj = {};
var YAxisPoint = Point.bind(emptyObj, 0 /*x*/);

var axisPoint = new YAxisPoint(5);
axisPoint.toString(); // '0,5'

axisPoint instanceof Point; // true
axisPoint instanceof YAxisPoint; // true
new Point(17, 42) instanceof YAxisPoint; // true

//  JavaScript     
// ... 

//      
// (   )
YAxisPoint(13);

emptyObj.x + "," + emptyObj.y;
// >  '0,13'

var slice = Array.prototype.slice;

// ...

slice.apply(arguments);

//   "slice" 
var unboundSlice = Array.prototype.slice;
var slice = Function.prototype.apply.bind(unboundSlice);

// ...

slice(arguments);

if (!Function.prototype.bind) {
  Function.prototype.bind = function (oThis) {
    if (typeof this !== "function") {
      // ECMAScript 5  IsCallable 
      //    
      throw new TypeError(
        "Function.prototype.bind - what is trying to be bound is not callable",
      );
    }

    var aArgs = Array.prototype.slice.call(arguments, 1),
      fToBind = this,
      fNOP = function () {},
      fBound = function () {
        return fToBind.apply(
          this instanceof fNOP ? this : oThis,
          aArgs.concat(Array.prototype.slice.call(arguments)),
        );
      };

    if (this.prototype) {
      // Function.prototype prototype  
      fNOP.prototype = this.prototype;
    }
    fBound.prototype = new fNOP();

    return fBound;
  };
}