<!DOCTYPE html>
<head>
<meta charset="UTF-8">
<title></title>
<script language="javascript">
function calc(){
let result=document.getElementById("result");
let n=document.getElementById("text").value;
if (n=="") {
result.innerHTML="请输入内容";
}else if (!(/(^[1-9]\d*$)/.test(n))) {
result.innerHTML="输入的不是正整数";
}else {
let s=0;
for(let i=1;i<=n;i++){
s+=i;
}
result.innerHTML="1到n累加和s="+s;
}
}
</script>
</head>
<body>
<input type="text" id="text"/>
<input type="button" value="计算" onclick="calc()"/>
<div id="result"></div>
</body>
</html>