const start = document.querySelector('#start');

const stop = document.querySelector('#stop');

const body = document.querySelector('body')

let startInterval;

// Hex color code generator.

let hex = '0123456789abcdef';

const colorId = function(){

let colorHex = "#";

for(let i = 0; i < 6; i++){

colorHex+= hex[Math.floor(Math.random()*16)];

}

return colorHex

};

// color setter

const changeColor = function(){

body.style.backgroundColor = colorId();

}

let intervalId;

// color change start

startInterval = function(){

if(!intervalId){

intervalId = setInterval(changeColor, 1000);

}

};

// start button click

start.addEventListener('click', startInterval);

// color change stop

let stopInterval = function(){

clearInterval(intervalId);

intervalId = null;

};

// stop button click

stop.addEventListener('click', stopInterval);