use strict not allow use of this in node.js

Question

After using 'use strict' statement in my js file it does not allow me to use javascript this after ist level

'use strict'

module.exports = {
  a: function() {
    var self = this //works fine upto this level
    var name = 'atul';
    function b() {
      this.name = name; //gives me error as can not set property name of undefined
    }
  }
}

man but i want t use this in the second function and i also want to make the scope of the variable inside function b — Atul Agrawal, Apr 26 '16 at 08:13
please check my answer the last part addresses using this in the function. @AtulAgrawal — Amresh Venugopal, Apr 26 '16 at 08:20
Possible duplicate of [Javascript "this" pointer within nested function](http://stackoverflow.com/questions/9644044/javascript-this-pointer-within-nested-function) — Krzysztof Safjanowski, Apr 26 '16 at 08:37
but that is working fine for me Javascript "this" pointer within nested function – Krzysztof Safjanowski — Atul Agrawal, Apr 26 '16 at 08:39

Amresh Venugopal · Accepted Answer · 2016-04-26T08:19:14.530

1

this and Javascript:

this references to the global object by default. ("window" on browsers)

this references to the calling object example:

var x = {name: "x", alphabet: function(){return this;}};
x.alphabet(); // in this line, x is the calling object

this will show you the object itself.

So when you do:

...
a: function() {
  var self = this //works fine upto this level
  var name = 'atul';
  function b() {
    this.name = name; //use strict is trying to tell you something
  }// you won't have a calling object for this function.
}
...

use-strict says: this function is not even an object property or method. Since it's not a method it's this will point to the global object and lead to error prone development.

If you wish to use your code in this particular way.

module.exports = {
  a: {
       name: 'atul';
       b: function (name) {
         this.name = name; // now you have a as the property which can be called by an object a.
         //To be used as OBJECT.a.b();
    }
  };
};

edited Apr 26 '16 at 08:19

answered Apr 26 '16 at 08:13

Amresh Venugopal

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i can also use by creating a blank object in function a and then call it by using obj.b – Atul Agrawal Apr 26 '16 at 08:23
If that's an answer do post it. if that's a question, I need to see the code :) @AtulAgrawal – Amresh Venugopal Apr 26 '16 at 08:26
var obj ={}; obj.b= function(){ this.name = name; //gives me error as can not read property name of undefined console.log(this.name); } obj.b(); – Atul Agrawal Apr 26 '16 at 08:31
this is basically the answer – Atul Agrawal Apr 26 '16 at 08:32
You have created a blank object first, then you are trying to set this.name to a name. you neither have name in the function nor this.name is a property. why? obj has no property called name. @AtulAgrawal – Amresh Venugopal Apr 26 '16 at 08:36
can we continue this on chat?? – Atul Agrawal Apr 26 '16 at 08:36
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/110225/discussion-between-atul-agrawal-and-amresh-venugopal). – Atul Agrawal Apr 26 '16 at 08:40

score -1 · Answer 2 · answered Apr 26 '16 at 08:09

this is undefined as it is not autoboxed to an object in strict mode.

First, the value passed as this to a function in strict mode is not forced into being an object (a.k.a. "boxed"). For a normal function, this is always an object: either the provided object if called with an object-valued this; the value, boxed, if called with a Boolean, string, or number this; or the global object if called with an undefined or null this. (Use call, apply, or bind to specify a particular this.) Not only is automatic boxing a performance cost, but exposing the global object in browsers is a security hazard, because the global object provides access to functionality that "secure" JavaScript environments must restrict. Thus for a strict mode function, the specified this is not boxed into an object, and if unspecified, this will be undefined

use strict not allow use of this in node.js

2 Answers2