用Ajax（javascript、XMLHttpRequest等）技术实现：

Question

用Ajax（javascript、XMLHttpRequest等）技术实现：

前端页面输入两个数值

后端服务完成两个数值相加

在前端页面显示从后端服务取得的两个数值相加后的结果

Answer 1

<script&nbsp;type="text/javascript">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; function&nbsp;AddNumbers()&nbsp; {&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;//&nbsp;Create&nbsp;an&nbsp;instance&nbsp;of&nbsp;the&nbsp;HTTP&nbsp;Request&nbsp;Object&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;xmlHttp&nbsp;=&nbsp;new&nbsp;XMLHttpRequest();&nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;value1&nbsp;=&nbsp;document.getElementById("txtValue1").value;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;value2&nbsp;=&nbsp;document.getElementById("txtValue2").value;&nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;//&nbsp;Specify&nbsp;HTTP&nbsp;POST&nbsp;so&nbsp;that&nbsp;parameters&nbsp;can&nbsp;be&nbsp;passed&nbsp;in&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;//&nbsp;request&nbsp;body&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;xmlHttp.open("POST",&nbsp;"add.aspx",&nbsp;false);&nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;//&nbsp;Send&nbsp;the&nbsp;parameters&nbsp;in&nbsp;CSV&nbsp;format&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;xmlHttp.send(value1&nbsp;+&nbsp;","&nbsp;+&nbsp;value2);&nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;result&nbsp;=&nbsp;document.getElementById("spanResult");&nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;//&nbsp;Use&nbsp;result&nbsp;of&nbsp;calculation&nbsp;from&nbsp;server&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;result.innerHTML&nbsp;=&nbsp;xmlHttp.responseText;&nbsp; }&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </script>&nbsp; ...&nbsp; <form>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;<input&nbsp;id="txtValue1"/>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;<input&nbsp;id="txtValue2"/>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;<input&nbsp;onclick="AddNumbers();"type="button"&nbsp;value="Add"/>&nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;<p>Result:</p>&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;<span&nbsp;id="spanResult"></span>&nbsp; </form>