<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<input type="text" id="scf">
<input type="submit" id="pf" value="评分">
<div id="txt"></div>
<script>
var scf=document.getElementById("scf");
var pf=document.getElementById("pf");
pf.onclick=function(){
var n=scf.value;
if(n=="")
{txt.innerHTML="请输入一个数字"
return;
}
if(isNaN(n)||(n<0||n>100))
{txt.innerHTML="数据非法"
return;
}
if(n>=0&&n<=100)
{
if(n>=90){
txt.innerHTML="优秀";
}
else if(n>=75){
txt.innerHTML="良好";
}
else if(n>=60){
txt.innerHTML="及格";
}
else if(n>=0)
{
txt.innerHTML="不及格";
}
}
}
</script>
</body>
</html>