JS 函数防抖

const debounce = function debounce(func, wait, immediate) {
        if (typeof func !== "function") throw new TypeError('func must be an function');
        if (typeof wait === "boolean") {
            immediate = wait;
            wait = 300;
        }
        if (typeof wait !== "number") wait = 300;
        if (typeof immediate !== "boolean") immediate = false;
        let timer;
        return function proxy(...params) {
            let runNow = !timer && immediate,
                self = this,
                result;
            if (timer) {
                clearTimeout(timer);
                timer = null;
            }
            timer = setTimeout(() => {
                if (timer) {
                    clearTimeout(timer);
                    timer = null;
                }
                if (!immediate) result = func.call(self, ...params);
            }, wait);
            if (runNow) result = func.call(self, ...params);
            return result;
        };
    };