Understanding how to bind scope in JavaScript with constructors

scope.js

Function.prototype.bind = function(scope) {
  _function = this;
  
  return function() {
    _function.apply(scope, arguments);
  }
}

window.scope = "window";

Object = function() {
  this.scope = "object";
  
  this.run = function() {
    var action = function(word) {
      console.log(word + " " + this.scope);
    }
    
    action.bind(this)("hello");
  }
}

obj = new Object();
obj.run()