看了好久没看出来问题，又不想用parseInt ，求大神赐教！

4回答

qq_位卑未敢忘忧国_0

<!DOCTYPE html><html><head> <title></title></head><body> <input type='text' name="txt1" id='txt1'/> <select id='select'> <option value='+'>+</option> <option value="-">-</option> <option value="*">*</option> <option value="/">/</option> </select> <input type='text' name="txt2" id='txt2'/> <input type='button' name="but" value='=' onclick="s()"/> <input type='text' name="te" id='fruit' value=""/></body></html><script type="text/javascript"> function s(){ var sum = document.getElementById("fruit"); var x = document.getElementById("txt1").value; var y = document.getElementById("txt2").value; var he =x*1+y*1; var cha =x*1-y*1;//减 var ji =x*y*1;//乘 var chu = x/y*1;//除 var select=document.getElementById("select").value; switch(select){ case "+": sum.value=he; break; case "-": sum.value=cha;break; case "*": sum.value=ji; break; case "/": sum.value=chu;break; default : sum.value="default"; } }</script>修改了下复制看看

qq_轉裑灬巳陌_0

<!DOCTYPE html> <html> <head> <title> 事件</title> <script type="text/javascript"> function count(){ var sum=0; var x=parseInt(document.getElementById("txt1").value); var y=parseInt(document.getElementById("txt2").value); var select=document.getElementById("select").value; switch(select){ case "+": sum=x+y;break; case "-": sum=x-y;break; case "*": sum=x*y;break; case "/": sum=x/y;break; default : sum="default"; break; } document.getElementById("fruit").value = sum; } </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>

Caballarii

switch(select){//select呢？document.getElementById("select")去哪儿了？ducument.getElementById("fruit").value = sum;这句怎么到了函数外面？document也拼错了