Using external javascript script in TypeScript

Question

Let's say I have a javascript file, myScript.js, with the following content:

function run(file) {
    // some operations
}

How can I use the 'run' function inside a TypeScript file?

I've read similar questions but didn't find their answers clear enough: where I declare the function? how do I reference the declaration file etc..

Possible duplicate of Using a 3rd party js file with TypeScript — Nitzan Tomer
– Nitzan Tomer, Commented Jul 4, 2016 at 10:06
I think that the other answers are not details enough. Where should I declare it? where is the reference to the js file? That's the information I'm looking for — yonisha
– yonisha, Commented Jul 4, 2016 at 10:21

Markus Johnsson · Accepted Answer · 2017-03-20 08:35:28Z

5

TypeScript does not know about the run function. You'll have to declare it:

declare function run(file: any): any;

Now this works:

run(myFile);

EDIT: you can also look into using "--allowJs" tsc parameter mentioned here, but I have no experience with it.

EDIT 2: If the external script is a published library, chances are that there is a typings file (.d.ts) for it. Check out the typings tool in that case.

edited Mar 20, 2017 at 8:35

answered Jul 4, 2016 at 10:07

Markus Johnsson

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5 Comments

yonisha Over a year ago

Where should I declare it? where is the reference to the js file?

Nitzan Tomer Over a year ago

You put it in a .d.ts file (myfile.d.ts) and you reference it: /// <reference path="myfile.d.ts" />

yonisha Over a year ago

@NitzanTomer thanks, now I can compile but I'm getting runtime error 'run is not defined'.

Nitzan Tomer Over a year ago

That probably means that you're not really including that actual js file and so run isn't defined

Markus Johnsson Over a year ago

You can declare it in same file (using 'declare' keyword). But you have to provide the script at runtime (e.g using a script tag)

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