<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<button onclick="buttom()">提交</button>
<div id="div1"></div>
</body>
<script>
function buttom() {
var q = '';
var count = 0;
for (var i = 20; i <= 80; i++) {
if (i % 3 == 0) {
q += i
if (count % 5 == 0) {
console.log(count);
document.getElementById('div1').innerHTML = q + "<br/>";
} else {
document.getElementById('div1').innerHTML = q;
};
count++
};
};
};
</script>
</html>你的算法有问题，不清楚你题目要求逻辑怎么写，算法有问题，和输出没问题
"document.getElementById('div1').innerHTML = q" 这句要放到for循环外面，原因就不多说了，自己看一下吧
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<button onclick="buttom()">提交</button>
<div id="div1"></div>
</body>
<script>
function buttom() {
var q = '';
var count = 0;
for (var i = 20; i <= 80; i++) {
if (i % 3 == 0) {
q += i;
count++
if (count % 5 == 0) {
q+="<br/>"
}
};
};
document.getElementById('div1').innerHTML = q;
};
</script>
</html>