In JS, `this` in object literals is untyped

[waderyan]

From Ilya Shuvalov (@ishuvalov) on September 20, 2016 7:54

• VSCode Version: Code 1.5.2 (66f37fd2a99eb9d628dd374d81d78835b410c39b, 2016-09-12T13:05:12.065Z)
• OS Version: Darwin x64 15.6.0

Steps to Reproduce:

1. Consider the following code:

(function(undefined) {
    MyView = Backbone.View.extend({
        secondFunc: function () {
            return;
        },

        mainFunc: function() {
            this.secondFunc()
        }
    });
})();

1. The Goto Definition, Peek Definition and other IntelliSense features are not working for this.secondFunc() call.

Copied from original issue: microsoft/vscode#12306

[waderyan]

From João Moreno (@joaomoreno) on September 20, 2016 8:17

Ilya Shuvalov (@ishuvalov) This is going to be very hard to get from the language service, because this isn't really bound to anything by semantically analysing the code. It's only due to the implicit knowledge of how Backbone.View.extend works.

You could try using TypeScript, you'd get those language features all the way.

[waderyan]

From Ilya Shuvalov (@ishuvalov) on September 20, 2016 8:38

João Moreno (@joaomoreno) Thank you for your comment! Let's omit Backbone

(function(undefined) {
    var myObj = {
        secondFunc: function () {
            return;
        },

        mainFunc: function() {
            this.secondFunc()
        }
    };
})();

Still not working. I understand the difficulties of this context, but the feature could work just finding all symbolic definitions in the workspace (or even just a current file) and allowing user to choose from. This how Sublime Text 3 works.
Unfortunately the TypeScript is not an option for my project.

[waderyan]

Ilya Shuvalov (@ishuvalov) thank you for opening this issue. I have repo'd this with JavaScript language service 2.0.2.

Sending this to the TypeScript team as they provide the JavaScript language service.

[mhegazy]

One option, in a .js file we can make the type of this to be the type of the containing object literal if no other better option is available.

[sandersn]

Basically, #8382, but only for JavaScript files, right? I think that could work.

[mhegazy]

i guess so.