TypeScript complains with and without lib

Question

I'm trying to add an async function in a TypeScript project. The code looks like this:

chrome.tabs.onUpdated.addListener(async (id, c, t) => { ... });

TypeScript complains:

error TS2705: An async function or method in ES5/ES3 requires the 'Promise' constructor. Make sure you have a declaration for the 'Promise' constructor or include 'ES2015' in your --lib option

When I add lib: ['es2015'] to tsconfig, TypeScript starts complaining about all calls to console.log saying that console is undefined.

Titian Cernicova-Dragomir · Accepted Answer · 2017-12-06 05:33:08Z

5

The default libs for es5 are DOM,ES5, so if you specify es2015 you will also need to add dom explicitly as console is defined in the dom library. Sample tsconfig.json:

{ "compilerOptions": { "target": "es5", "lib": [ "es2015", "dom" ] } }

Typescript has a modular approach to the default libraries, so you can include only what is available based on your environment.

edited Dec 6, 2017 at 5:33

answered Dec 5, 2017 at 7:53

Titian Cernicova-Dragomir

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5 Comments

zmbq Over a year ago

This almost works! tslint is still complaining about it! $#@$#@$#@. I'll just tell it to ignore this check.

zmbq Over a year ago

#@!#@!#!@ I couldn't find a way to disable this message! It's either tslint or PyCharm.

Titian Cernicova-Dragomir Over a year ago

What message are you getting ?

zmbq Over a year ago

It's PyCharm, not tslint (i've disabled tslint and the problem persists). I get a red squiggly line under the async callback with the exact same message - that there's no Promise constructor or es2015 is not in lib. The code transpiles and runs properly, so this is probably a PyCharm bug.

zmbq Over a year ago

I ended up putting the callback in its own async function and just pass that function to addListener. The code is now nicer looking and there's no squiggly red line.

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