Using TypeScript to create a generic type that wraps around HTMLElements

I attempted to execute this action, however the assignment to this.element is not working and I am unsure why.

class Elem<T> {
    public element : T;
    constructor(typeElement:string){
        this.element = document.createElement(typeElement);
    }
}

By visiting this playground link,

Answer №1

It seems that your example is almost correct, except for the fact that T should indicate an extension of HTMLElement, and then you must cast HTMLElement to type T within the constructor.

//         cast T as type HTMLElement
class Elem<T extends HTMLElement> {
    public element: T;
    constructor(typeElement: string) {
        // had to cast HTMLElement to type T....
        // odd because T extends HTMLElement, but it works
        this.element = <T>document.createElement(typeElement);
    }
}

var e = new Elem('div');
e.element.innerHTML = 'generic class test';
document.body.appendChild(e.element);

You can witness its functionality in the playground

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