如何更改对象属性的值

Question

I have problem with understanding one aspect.

var Car = function(name, loc) {
    'use strict';
    this.name = name;
    this.loc = loc;
    this.methods = {
        move: function() {
           this.loc++;
        },
        show: function() {      
            console.log('Position of ' + this.name + ' is: ' + this.loc);
        }
    };
};
var amy = new Car('amy', 1);
var ben = new Car('ben', 9);

When I use this.loc++ it's referring to methods object, not to Car object. And location of car is not incremented. My question is how to jump to car object context from methods?

Answer 1

You can save parent context to variable ( var _this = this; ), like this

 var Car = function(name, loc) { 'use strict'; var _this = this; this.name = name; this.loc = loc; this.methods = { move: function() { _this.loc++; }, show: function() { console.log('Position of ' + _this.name + ' is: ' + _this.loc); } }; }; var amy = new Car('amy', 1); var ben = new Car('ben', 9); amy.methods.move(); amy.methods.move(); amy.methods.show();