Javascript 自制range函数实现

function range(start, stop, step){    if (typeof(stop) == 'undefined')    {        // one param defined        stop = start;        start = 0;    }    if (typeof(step) == 'undefined')    {        step = 1;    }    if ((step > 0 && start >= stop) || (step < 0 && start <= stop))    {        return [];    }    var result = [];    for (var i = start; step > 0 ? i < stop : i > stop; i += step)    {        result.push(i);    }    return result;}