Can I define a Typescript function parameter to have a type of boolean or string?

Issue

I have this function:

network = (action: boolean): void => {
    if (action) {
        this.action = action;
        this.net = true;
        this.netd = true;
    } else {
        this.action = null;
        this.net = false;
        this.netd = false;
    }
}

Is there a way that I can define in typescript that the action can have a value of boolean OR string?

Solution

Yes. Just use a function instead of var:

function network(action:boolean):void;
function network(action:string):void;
function network(action: any): void {
    if (action) {
        this.action = action;
        this.net = true;
        this.netd = true;
    } else {
        this.action = null;
        this.net = false;
        this.netd = false;
    }
}

network(''); //okay
network(true); // okay
network(12); // ERROR!

Its called function overloading and you can do this for member functions as well.

Answered By - basarat