本文实例讲述了JavaScript编写简单计算器的代码。分享给大家供大家参考。具体如下：
运行效果截图如下：
具体代码如下
<!DOCTYPE html><html lang="en"><head> <meta charset="utf-8"> <title>计算器</title> <style> /*Basic reset*/*{ margin:0; padding:0; box-sizing: border-box; font: 14px Arial,sans-serif;}html{ height:100%; background-color:lightslategrey;}#calculator{ margin: 15px auto; width:330px; height:400px; border: 1px solid lightgray; background-color:darkgrey; padding:15px;}/*LOGO*/.LOGO{ height:20px;}.LOGO .name{ float:left; line-height:30px;}.LOGO .verson{ float:right; line-height:30px;}/*screen*/#shuRu{ margin-top:15px;}.screen{ margin-top:5px; width:300px; height:40px; text-align: right; padding-right:10px; font-size:20px;}#keys{ border:1px solid lightgray; height:223px; margin-top:25px; padding:8px;}#keys .last{ margin-right:0px;}.footer{ margin-top:20px; height:20px;}.footer .link{ float:right;}#keys .buttons{ float:left; width: 42px; height: 36px; text-align:center; background-color:lightgray; margin: 0 17px 20px 0;} </style></head><body><div id="calculator"> <div class="LOGO"> <span class="name">简单的计算器</span> <span class="verson">@walker</span> </div> <div id="shuRu"> <!--screen输入栏--> <div class="screen"> <input type="text" id="screenName" name="screenName" class="screen"> </div> </div> <div id="keys"> <!-- j --> <!--第一排--> <input type="button" id="7" onclick="jsq(this.id)" value="7" class="buttons"> <input type="button" id="8" onclick="jsq(this.id)" value="8" class="buttons"> <input type="button" id="9" onclick="jsq(this.id)" value="9" class="buttons"> <input type="button" id="Back" onclick="tuiGe()" value="Back" class="buttons"> <input type="button" id="C" onclick="clearNum()" value="C" class="buttons" style="margin-right:0px"> <!--第二排--> <input type="button" id="4" onclick="jsq(this.id)" value="4" class="buttons"> <input type="button" id="5" onclick="jsq(this.id)" value="5" class="buttons"> <input type="button" id="6" onclick="jsq(this.id)" value="6" class="buttons"> <input type="button" id="*" onclick="jsq(this.id)" value="X" class="buttons"> <input type="button" id="/" onclick="jsq(this.id)" value="/" class="buttons" style="margin-right:0px"> <!--第三排--> <input type="button" id="1" onclick="jsq(this.id)" value="1" class="buttons"> <input type="button" id="2" onclick="jsq(this.id)" value="2" class="buttons"> <input type="button" id="3" onclick="jsq(this.id)" value="3" class="buttons"> <input type="button" id="+" onclick="jsq(this.id)" value="+" class="buttons"> <input type="button" id="-" onclick="jsq(this.id)" value="-" class="buttons" style="margin-right:0px"> <!--第四排--> <input type="button" id="0" onclick="jsq(this.id)" value="0" class="buttons"> <input type="button" id="00" onclick="jsq(this.id)" value="00" class="buttons"> <input type="button" id="." onclick="jsq(this.id)" value="." class="buttons"> <input type="button" id="%" onclick="jsq(this.id)" value="%" class="buttons"> <input type="button" id="eva" onclick="eva()" value="=" class="buttons" style="margin-right:0px"> </div> <div class="footer"> <span class="aside">欢迎使用JavaScript计算器</span> <span class="link"> <a href="#" title="声明" target="_blank">反馈</a> </span> </div></div></body></html>js代码：
<script> var num = 0; // 定义第一个输入的数据 function jsq(num) { //获取当前输入 if(num=="%"){ document.getElementById('screenName').value=Math.round(document.getElementById('screenName').value)/100; }else{ document.getElementById('screenName').value += document.getElementById(num).value; } } function eva() { //计算输入结果 document.getElementById("screenName").value = eval(document.getElementById("screenName").value); } function clearNum() { //清0 document.getElementById("screenName").value = null; document.getElementById("screenName").focus(); } function tuiGe() { //退格 var arr = document.getElementById("screenName"); arr.value = arr.value.substring(0, arr.value.length - 1); }</script>一个简单的计算器就是这样实现的，大家也可以利用javascript编写计算器，，希望对大家的学习有所帮助。
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