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Correction status：qualified
Teacher's comments：
Collection
Collection
简易计算器：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>计算器</title>
</head>
<body>
<input type="test" name="num" placeholder="输入数字1" id = "num1"/>
<select id="oper">
<option value="">请选择运算符</option>
<option value="plus">+</option>
<option value="minus">-</option>
<option value="mul">x</option>
<option value="div">/</option>
</select>
<input type="test" name="num" placeholder="输入数字2" / >
<br><br>
<button type="button" id ="check" >计算</button><span style="color:red;padding-left:30px;" class="wrong"></span>
<br><br><div>结果为：<span id="res"></span></div>
<script type="text/javascript">
let button = document.getElementById('check');
button.onclick = function(){
let oper = document.getElementById('oper');
let res = document.getElementById('res');
let num= document.getElementsByName('num');
// alert(num[0].value + num[1].value);
// alert(oper);
if(num[0].value == "" || num[0].value.length==0 || num[1].value == "" || num[1].value.length==0){
show_wrong("数字1或数字2不能为空");
}else{
res.innerHTML = "";
num1 = parseInt(num[0].value)
num2 = parseInt(num[1].value)
switch(oper.value){
case "plus":
result = num1 +num2
str = num1 + '+' + num2 + '=' + result;
res.innerHTML = str;
break;
case "minus":
result = num1 - num2
str = num1 + '-' + num2 + '=' + result;
res.innerHTML = str;
break;
case "mul":
result = num1*num2
str = num1 + '乘' + num2 + '=' + result;
res.innerHTML = str;
break;
case "div":
if(num2==0){
show_wrong('除数不能为0')
break;
}
result = num1/num2
str = num1 + '除' + num2 + '=' + result;
res.innerHTML = str;
break;
default:
show_wrong("请选择操作符号");
break;
}
}
}
function show_wrong(str){
document.getElementsByClassName('wrong')[0].innerHTML = str;
}
</script>
</body>
</html>点击 "运行实例" 按钮查看在线实例
