函数防抖

// 函数防抖
export function debounce (func, delay = 300, immediate = false) {
    let timer = null
    return function () {
        if (timer) {
            clearTimeout(timer)
        }
        if (immediate && !timer) {
            func.apply(this, arguments)
        }
        timer = setTimeout(() => {
            console.log(this, arguments)
            func.apply(this, arguments)
        }, delay)
    }
}