debounce函数缺陷

[PRC-Cc]

https://github.com/scofieldfan/turtle-rock/blob/e4598498e434836d0dcf0a40f1408d4ca02b73fc/src/util.js#L5

debounce(fun, delay, immediate) {
    let timer = null;
    return (...args) => {
        if (timer) { // 去掉判断语句即可
            clearTimeout(timer);
        } else {
            timer = setTimeout(() => {
                fun.apply(this, args);
            }, delay);
        }
    };
}