JS Bind Implementation

bind.js

Function.prototype.bind1 = function (scope) {
  let fn = this
  let prefixArgs = Array.prototype.slice.call(arguments, 1)
  
  return function() {
    let suffixArgs = Array.prototype.slice.call(arguments)
    let args = prefixArgs.concat(suffixArgs)
    return fn.apply(scope, args)
  } 
}


function sum() {
 var _sum = 0
 for (var i = 0; i < arguments.length ; i++) {
     _sum += arguments[i];
 }
 return _sum;
}
var sum_plus_two = sum.bind1({},2);


console.log(sum_plus_two(5,7))



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

var unboundGetX = module.getX;

var boundGetX = unboundGetX.bind1(module);

console.log(boundGetX());



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

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

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

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

// Create a function with a preset leading argument
var leadingThirtysevenList = list.bind(null, 37);

// Create a function with a preset first argument.
var addThirtySeven = addArguments.bind(null, 37); 

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

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

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

var result3 = addThirtySeven(5, 10);
// 37 + 5 = 42 , second argument is ignored

console.log(list2);
console.log(list3)
console.log(result2);
console.log(result3)