classnames.ts

type Param = string | number | string[] | {[key: string]: boolean}[] | {[key: string]: boolean};

export function classnames(...args: Param[]) {
    if (args.length === 0) {
        return '';
    } else {
        return args
            .map(item => rec(item))
            .join(' ');
    }
}

export const cn = classnames;

function rec(param: Param) {
    if (param === null || param === undefined) {
        return '';
    } else if (typeof param === 'string') {
        return param;
    } else if (typeof param === "number") {
        return param + '';
    } else if (Array.isArray(param)) {
        return classnames.apply({}, param);
    } else if (typeof param === 'object') {
        return Object
            .entries(param)
            .filter(([, condition]) => !!condition)
            .map(([name]) => name)
            .join(' ');
    } else {
        return '';
    }
}