防抖节流函数

防抖

export const debounce = (fn, delay) => {
    let timer = null;
    let that = this;
    return (...args) => {
        timer && clearTimeout(timer)
        timer = setTimeout(() => {
            fn.apply(that, args);
        }, delay);
    }
}

节流

// 定时器版
export const throttle = (fn, delay) => {
    let timer = null;
    let that = this;
    return (args) => {
        if (timer) return;
        timer = setTimeout(() => {
            fn().apply(that, args);
            timer = null;
        }, delay);
    }
}



// 时间戳版
function throttle(fn, delay) {
    var previous = 0;
    // 使用闭包返回一个函数并且用到闭包函数外面的变量previous
    return function() {
        var _this = this;
        var args = arguments;
        var now = new Date();
        if(now - previous > delay) {
            fn.apply(_this, args);
            previous = now;
        }
    }
}