防抖

myDebounce(fun, time,immediate=false) {
    let timer;
    let isvoken = false
    return function(...arg) {
        if(immediate && !isvoken) {
            fun.call(this, ...arg);
            isvoken = true
        } else {
            if (timer) {
                clearTimeout(timer);
            }
            timer = setTimeout(() => {
                fun.call(this, ...arg);
                isvoken = false
            }, time);
        }
    };
}