extending typescript lib.d.ts, where to commit changes to

Question

According to https://developer.mozilla.org/en-US/docs/Web/API/FileReader

interface FileReader extends MSBaseReader {
    error: DOMError;
    readAsArrayBuffer(blob: Blob): void;
    readAsDataURL(blob: Blob): void;
    readAsText(blob: Blob, encoding?: string): void;
}
declare var FileReader: {
    prototype: FileReader;
    new (): FileReader;
}

this from lib.d.ts should also have DONE,LOADING,EMPTY on the variable. How can I extend this, and do lib.d.ts has a public place where such changes can be committed to?

Fenton · Accepted Answer · 2013-10-18 12:58:47Z

4

To get access to new properties before they are added to lib.d.ts you can extend the declarations. This can be done because interfaces in TypeScript are open.

So add a TypeScript file called something like libextensions.ts and add the following:

interface FileReader {
    EMPTY: number;
    LOADING: number;
    DONE: number;
}

You only need to put the missing bits here - they will be added to the lib.d.ts interface.

You can use this technique to stay up to date with working drafts and the compiler will tell you when lib.d.ts has been updated by issuing a duplicate declaration error.

If you have an instance of a FileReader, you don't need to access the constant via FileReader.prototype.DONE you can use the constant on the instance - example:

var fileReader = new FileReader();
var example = fileReader.DONE;

edited Oct 18, 2013 at 12:58

answered Oct 18, 2013 at 7:37

Fenton

253k74 gold badges404 silver badges414 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Poul K. Sørensen Over a year ago

Problem was that I was converting some existing javascript and it had FileReader.DONE, so to use that I had to add it to the variable FileReader and not the interface. (realized I should do FileReader.prototype.DONE instead - its already there)

Fenton Over a year ago

If you have an instance of a file reader, you don't need to go via the prototype - I have added an example to my answer - and indeed it is already available in TypeScript: typescriptlang.org/Playground/…

Poul K. Sørensen Over a year ago

I have been thinking that DONE was like a static type on FileReader. Just need to get used to the way javascript works.

basarat · Accepted Answer · 2013-10-17 22:32:28Z

0

You should open a bug report here : http://typescript.codeplex.com/workitem/list/basic The typescript team manages lib.d.ts

answered Oct 17, 2013 at 22:32

basarat

278k61 gold badges475 silver badges528 bronze badges

1 Comment

Poul K. Sørensen Over a year ago

I was a little fast, found out the DONE was on the prototype.

Collectives™ on Stack Overflow

extending typescript lib.d.ts, where to commit changes to

2 Answers 2

3 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related