<!DOCTYPE?html><html><head><meta?charset="UTF-8"?/><title>Document</title><script>window.onload=function(){var?oN1=document.getElementById('n1').value;var?oN2=document.getElementById('n2').value;var?oBtn=document.getElementById('btn');var?oResult="";var?oObj=document.getElementById('obj').value;switch(oObj){case?'+':oResult=parseFloat(n1)+parseFloat(n2);break;case?'-':oResult=parseFloat(n1)-parseFloat(n2);break;case?'*':oResult=parseFloat(n1)*parseFloat(n2);break;case?'/':oResult=parseFloat(n1)/parseFloat(n2);break;}oBtn.onclick=function(){document.getElementById('result').value=oResult;}}</script></head><body><input?type="text"?id="n1"/><select?name=""?id="obj"?><option?value="+">+</option><option?value="-">-</option><option?value="*">*</option><option?value="/">/</option></select><input?type="text"?id="n2"/><input?type="button"?value="="?id="btn"/><input?type="text"?id="result"/></body></html>
2018-08-31
<!DOCTYPE?html><html><head><meta?charset="UTF-8"?/><title>Document</title><script>window.onload=function(){var?oBtn=document.getElementById('btn');oBtn.onclick=function?toSum(){var?oN1=document.getElementById('n1').value;var?oN2=document.getElementById('n2').value;var?oObj=document.getElementById('obj').value;var?oResult='';switch(oObj){case?'+':oResult=parseFloat(oN1)+parseFloat(oN2);break;case?'-':oResult=parseFloat(oN1)-parseFloat(oN2);break;case?'*':oResult=parseFloat(oN1)*parseFloat(oN2);break;case?'/':oResult=parseFloat(oN1)/parseFloat(oN2);break;}document.getElementById('result').value=oResult;}}</script></head><body><input?type="text"?id="n1"/><select?name=""?id="obj"?><option?value="+">+</option><option?value="-">-</option><option?value="*">*</option><option?value="/">/</option></select><input?type="text"?id="n2"/><input?type="button"?value="="?id="btn"/><input?type="text"?id="result"/></body></html>關于此題的寫法，我把所有人的答案全看了，最后的點擊事件全都是寫的行內(nèi)JS代碼，沒有一個人把整體JS全都寫到script中。以下是一種非行間JS的寫法。