Declaring the type of 'this' in a typescript function?

Question

I'm writing a grunt task in TypeScript. I'm trying to translate something I already have in JavaScript.

So, when grunt runs a task, it runs a function. When it runs, grunt sets this to an object with useful properties, the same way that jQuery overloads this with the element you are working on. I could access useful properties like this.files;

grunt.registerMultiTask('clean', function() {
    this.files.forEach(function(f) { Delete(f); });
});

So, "delete all the files in this.files".

However, in TypeScript, I don't know if you can 'hint' to the compiler that this is a particular type, so I don't get intellisense. How do I tell TypeScript to consider this to be a different type?

question from:https://stackoverflow.com/questions/65889651/how-to-type-a-function-which-is-on-proto-with-typescript

Answer 1

How do I tell TypeScript to consider this to be a different type

You can do that by declaring a this parameter. For your use case I've added this: {files:any[]}:

grunt.registerMultiTask('clean', function(this: {files:any[]}) {
    this.files.forEach(function(f) { Delete(f); });
});

More

• Official docs on this parameter