无法访问js文件中的名称空间变量

Question

a.js

// @global-constants
var App = {

  constant: function() {
    constant.prototype.CONST1 = 'abc';
  }

};

module.exports = App;

not able to access in say b.js using App.constant.CONST1 , it says undefined why?

Answer 1

there are two problems with you code:

1.) App.constant would return a class(technically a function), but what you want is it's object, can be created using a new keyword, so it becomes, (new App.constant).CONST1 .

2.) constant.prototype.CONST1 would not work, because constant is not the name of your anonymous function, so I gave it a name foo and it becomes foo.prototype.CONST1 .

the modified code:

var App = {
    constant: function foo() {
    foo.prototype.CONST1 = 'abc';
  }

};

console.log((new App.constant).CONST1);

fiddle demo .

Answer 2

If you just want to create a set of "constants", all you need is an object:

// @global-constants
var App = {

  constant: {
      CONST1: 'abc';
  }

};

To learn more about how prototypes work (so that you know when to use them and when not), I recommend to read this article on MDN .