noomorph/github-user-rank-extension

export function h(tag: string = 'div', props: {} = {}, children: any = []) {
    return {
        tag,
        props,
        children
    };
}

export function render(element: null): null;
export function render(element: undefined): undefined;
export function render(element: string): Node;
export function render(element: number): Node;
export function render(element: {}): Node;
export function render(element: Node): Node;
export function render(element: Node[]): Node[];
export function render(element: any): any {
    if (typeof element === 'string' || typeof element === 'number') {
        return document.createTextNode(String(element));
    }

    if (!element || isNode(element)) {
        return element;
    }

    if (Array.isArray(element)) {
        return element.map(render);
    }

    if (typeof element.tag !== 'string') {
        return null;
    }

    const {tag, props} = element;
    const el = document.createElement(tag);
    Object.assign(el, props);
    const children = wrapInArray(render(element.children));

    children.filter(node => {
        if (!isNode(node)) {
            console.log('weird child node in', tag, '\n', node, children);
            return false;
        }

        return true;
    }).forEach(childEl => el.appendChild(childEl));

    return el;
}

function isNode(element: any): element is Node {
    return element && element instanceof Node;
}

function wrapInArray<T>(value: T | T[]): T[] {
    return Array.isArray(value) ? value : [value];
}