JS的防抖与节流

防抖（debounce）

// 不需要立即执行的
let t;
$(window).on('scroll', function () {
        clearTimeout(t);
        t = setTimeout(function () {
            console.log(1);
        }, 100)
    }
})

// 需要立即执行的（改进）
let t;
let flag = true;
$(window).on('scroll', function () {
    if (flag) {
        // Do someting...
        flag = false;
        clearTimeout(t);
        t = setTimeout(function () {
            flag = true;
        }, 100)
    }
})

节流 (throttle)

/**
 * @param fn            方法
 * @param wait          间隔时间ms
 * @param immediately   是否立刻执行
 */
function throttle(fn: Function, wait: number, immediately: boolean = true) {
    let timer = null;
    let prev = null;
    let exceed = false;
    return function() {
        let now = new Date().getTime();
        if (!prev) prev = now;
        if (immediately && !exceed) {
            exceed = true;
            fn();
            return
        }
        if (now - prev > wait) {
            fn();
            prev = now;
            return
        }
        clearTimeout(timer);
        timer = setTimeout(fn, wait)
    }
}