bg_change_every_second.js

//generate a random color
const randomColor = function(){
    const hex = "0123456789ABCDEF"
    let color = '#'
    for (let i = 0; i < 6 ; i++) {
       color += hex[Math.floor(Math.random() * 16)]
        
    }
    return color
};
let intervalId;
const startChangingColor = function(){

    if(!intervalId){
        intervalId = setInterval(changeBgColor,1000)
    }
    
    function changeBgColor(){
        document.body.style.backgroundColor = randomColor();
    }
};
const stopChangingColor = function(){
    clearInterval(intervalId);
    intervalId = null
}

document.querySelector('#start').addEventListener
('click',startChangingColor)


document.querySelector('#stop').addEventListener
('click',stopChangingColor)