Anonymous Functions with parameters in Typescript

Question

I'm trying to create an anonymous function in typescript with parameters I'm trying the following format:

(function ($, undefined) => {})(jQuery);

I'm trying to create a definition file for an existing js libary called jQuery-total-storage.js

What is the proper format?

I'm new to Typescript.

possible duplicate of How can I declare a function from another file in Typescript? — Paul Turner
– Paul Turner, Commented Mar 3, 2014 at 15:14

Paul Turner · Accepted Answer · 2014-03-03 17:17:40Z

1

You can't really define an external function with a lambda expression - a lambda is an implementation not an interface. It can't be used to only express a contract, because it also expresses how that contract is implemented.

If you need to define an external function, you need to define one as part of an interface.

Looking at the jQuery Total Storage library, it seems to extend from the jQuery singleton. To extend from here, you must extend the JQueryStatic interface (as defined by DefininitelyTyped), adding the extended operations.

interface JQueryStatic {
    totalStorage(key: string, value: any): void;
    totalStorage(key: string): any;
}

Interfaces are just strongly-typed declarations. In this case, it's adding type information to the external library.

To be clear: you can only add type information, you can't change the signatures.

edited Mar 3, 2014 at 17:17

answered Mar 3, 2014 at 15:13

Paul Turner

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2 Comments

ryokan Over a year ago

Can this be an anonymous function of the interface? IE: interface JQueryTotalStorage extends JQuery { ($, undefined): void; totalStorage: (key, value, options) => any; setItem: (key, value) => any; getItem: (key) => any; getAll: () => any; } ($, undefined) => { bla bla

Paul Turner Over a year ago

You can declare a function with no name in an interface, which makes instances of the interface act like a functional delegate. Looking at the actual library, I don't see what you would map to an anonymous delegate - they're all identified by names.

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