看到很多都是用的switch,我特意寫了個用if的方式
<!DOCTYPE html>
<html>
?<head>
? <title> 事件</title>??
? <script type="text/javascript">
? function count(){
? var num1 = parseInt(document.getElementById("txt1").value);
? var num2 = parseInt(document.getElementById("txt2").value);
? var character = document.getElementById("select").value;
? var result;
? if(character=="+"){
? result = num1+num2;
? }
? else if(character=="-"){
? result = num1-num2;
? }
? else if(character=="*"){
? result = num1*num2;
? }
? else if(character=="/"){
? result = num1/num2;
? }
? else{
? result = null;
? }
??
? document.getElementById("fruit").value = result;
?}
??
? </script>
</head>
<body>
<input type = "text" id = "txt1"/>
<select id = "select">
? ? <option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select>
<input type = "text" id = "txt2"/>
<input type = "button" value = "=" onClick="count()"/>
<input type = "text" id = "fruit"/>
</body>
</html>
2019-11-18
有什么問題嗎？