Declare a delegate type in Typescript

Question

Coming from a C# background, I want to create a datatype that defines a function signature. In C#, this is a delegate declared like this:

delegate v         


        

Answer 1

You can create something like a delegate by using a type alias:

type MyDelegate = (input: string) => void;

which defines a type name for a function pointer, just as delegates do in C#. The following example uses it in combination with generic type parameters:

type Predicate = (item: T) => boolean;

export class List extends Array {
    constructor(...items: T[]){
        super();
        for(let i of items || []){
            this.push(i);
        }
    }
    public hasAny(predicate?: Predicate): boolean {
        predicate = predicate || (i => true)
        for(let item of this) {
            if(predicate(item)) return true;
        }
        return false;
    }
}