<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> <style> .div1{ position: fixed; top:0px; left:0px; bottom:0px; right:0px; } </style> </head> <body> <button class="div1" type="button" style="border:1px solid red">点击切换</button> <script> function cut(){ var str='#' let arr=['0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'] for(var i=0;i<6;i++){ let number=parseInt(Math.random()*16); // console.log(number); str+=arr[number] // console.log(str); } return str; } var div=document.getElementsByClassName('div1')[0] div.onclick=function(){ div.style.backgroundColor=cut(); } </script> </body> </html>