SOURCE

function debounce(fn, delay = 1000) {
    let timer = null
    return function(...args) {
        clearTimeout(timer)
        timer = setTimeout(() => {
            fn.apply(this, args)
        }, delay)
    }
}

function throttle(fn, delay = 1000) {
    let timer = null
    let startTime = Date.now()

    return function(...args) {
        const currentTime = Date.now()
        const remainingTime = delay - (currentTime - startTime)
        clearTimeout(timer)
        if (remainingTime < 0) {
            fn.apply(this, args)
            startTime = Date.now()
        } else {
            timer = setTimeout(() => {
                fn.apply(this, args)
            }, remainingTime)
        }
    }
}

function sayHi() {
    console.log('debounce....')
}

const input = document.querySelector('#myinput')
// input.addEventListener('input', debounce(sayHi))
input.addEventListener('input', throttle(sayHi, 2000))

<input id="myinput">