Typescript cannot find method in definition file

Question

I have an existing Javascript file named app.min.js which comes with a website template. This file defines a function called pageSetUp that needs to be invoked when the DOM is loaded.

I have created a TypeScript definition file named app.d.ts which the following content:

interface App {
    pageSetUp();
}

It is referenced in the TypeScript file as follows:

/// <reference path="../typings/app.d.ts"/>

However, when add the following line to the constructor of this class like this:

module ViewModel {

    export class TableViewModel {


        constructor() {
           pageSetUp();
        }
     }
}

The build fails with error: "Could not find symbol 'pageSetUp'.

What am I missing?

TIA.

Answer 1

app.d.ts is defining a method on an interface called App , but the TableViewModel is trying to use a global function called pageSetUp , which is not defined.

Try this instead in app.d.ts :

declare function pageSetUp();

This declares a global function, but doesn't implement it, so no associated JavaScript is generated, but the function definition can be referenced from other TypeScript files.