CODEWITHSUNDEEP
node.jsvisual-studio-code
Martin Braun
Martin Braun

Reputation: 12639

No code suggestions for global defined variables in VSCode in a node.js server project

I have to deal with a node.js server project that uses global variables for common APIs. For instance in the entry point server.js there is a Firebase variable for the real-time database that is stored like this:

fireDB = admin.database();

I wasn't aware that this is possible and I would consider this a bad approach, but now I have to deal with it.

I'm not really interested to re-write any of the many calls to this variable in all those files, rather I would find a way to make fireDB show me suggestions only by changing this variable or installing an extension.

I tried to define it on top of the file as var fireDB, but then suggestions only work in the same file, not in others.

When I set a dot behind admin.database() the suggestions work, when I write fireDB. I get no suggestions, yet the call seems to be possible. Suggestions need to work in other files, too. How can I get this to work?

No suggestions

Upvotes: 0

Views: 1445

Answers (1)

user3781737
user3781737

Reputation: 1022

WARNING: MAKE SURE YOU UNDERSTAND THE PROBLEMS WITH GLOBALS BEFORE USING THEM IN A PROJECT

The above warning/disclaimer is mostly for anyone starting a new project that might happen across this answer.

With that out of the way, create a new .d.ts file and put it somewhere with a descriptive name. For example, globals.d.ts at the top level of the directory. Then just populate it with the following (I don't have any experience with firebase, so I had to make some assumptions about which module you're using, etc.):

globals.d.ts

import { database } from "firebase-admin";

declare global {
    var fireDB: database.Database;
}

IntelliSense should then recognize fireDB as a global of the appropriate type in the rest of your JavaScript project.

Why does this work? IntelliSense uses TypeScript even if you're working with a JS project. Many popular JS packages includes a .d.ts file where typings are declared, which allows IntelliSense to suggest something useful when you type require('firebase-admin').database(), for example.

IntelliSense will also automatically create typings internally when you do something "obvious", e.g. with literals:

const MY_OBJ = { a: 1, b: "hello"};

MY_OBJ. // IntelliSense can already autocomplete properties "a" and "b" here

Global autocompletion isn't one of those "obvious" things, however, probably because of all the problems with global variables. I'd also guess it'd be difficult to efficiently know what order your files will run in (and hence when a global might be declared). Thus, you need to explicitly declare your global typings.

If you're interested in further augmenting the capabilities of IntelliSense within your JS project, you can also use comments to explicitly create typings:

/**
 * @param {String[]} arrayOfStrings 
 */
function asAnExample(arrayOfStrings) {
    arrayOfStrings. // IntelliSense recognizes this as an array and will provide suggestions for it
}

See this TypeScript JSDoc reference for more on that.

Upvotes: 2

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