<!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 select1=document.getElementById("select").value; var num=""; switch(select1){ case "+": num=txt1+txt2; break; case "-": num=txt1-txt2; break; case "*": num=txt1*txt2; break; case "/": num=txt1/txt2; break; } document.getElementById('fruit').value=num; </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()" /> <!--通过 = 按钮来调用创建的函数，得到结果--> <input type='text' id='fruit' /> </body></html>
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