SOURCE

//它将一个函数从可调用的 f(a, b, c) 转换为可调用的 f(a)(b)(c)
function curry(fn,arity = fn.length) {
    return (function nextCurried(prevArgs){
        return function curried(nextArg){
            var args = prevArgs.concat( [nextArg] );

            if (args.length >= arity) {
                return fn( ...args );
            }
            else {
                return nextCurried( args );
            }
        };
    })( [] );
}