参考部分资料，编写一个简单的计算器案例，虽然完成了正常需求，但是也有不满之处，待后续实力提升后再来补充，先把不足之处列出：
1：本来打算只要打开页面，计算器的输入框会显示一个默认为0的状态，但是在输入框加入默认显示为0的时候，选择数据输入时，该0会显示输入数字的前面，例如”0123“，由于能力有限，待后续实力提升再来补充完善！
2：目前只能实现鼠标控制选择按钮，待完善键盘录入功能。
3：乘法的那个符号在本来想改成”ד这个符号的，待后续完善。
附图片一张：
html部分：
<!DOCTYPE html><html lang="en"><head> <meta charset="utf-8"> <title>计算器</title></head><body onload="onLoad()"><div id="calculator"> <div class="LOGO"> <span class="name">简单的计算器</span> <span class="verson">@liumobai v1.0</span> </div> <div id="shuRu"> <!--screen输入栏--> <div class="screen"> <input type="text" id="screenName" name="screenName" class="screen" value="" onfocus="jsq(this)"> </div> </div> <div id="keys"> <!-- operators and other keys --> <!--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="*" 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部分：
<script> var num = 0; // 定义第一个输入的数据 function jsq(num) { //获取当前输入 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); } function onLoad(){ //加载完毕后光标自动对应到输入框 document.getElementById("screenName").focus(); }</script>CSS部分：
/*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;}接下来再给大家分享一则实例
<html><head> <title>Untitled</title> <style type="text/css"> input[type=button] { width:25px; height:25px; } </style> <script type="text/javascript"> var result=0; var point=false; //判断是小数点前还是后 var multiple=0.1; //初始化小数点后的倍率 var sort=0; //标记加减乘除 var temp=0; //记录上一轮结果 function onbutton0() //数字按钮动作 { var name=document.getElementByIdx_x("show"); if(!point) result=10*result+0; //小数点前的处理 else //小数点后的处理 { result=result+multiple*0; multiple=multiple*0.1; } name.value=String(result); } function onbutton1() { var name=document.getElementByIdx_x("show"); if(!point) result=10*result+1; else { result=result+multiple*1; multiple=multiple*0.1; } name.value=String(result); } function onbutton2() { var name=document.getElementByIdx_x("show"); if(!point) result=10*result+2; else { result=result+multiple*2; multiple=multiple*0.1; } name.value=String(result); } function onbutton3() { var name=document.getElementByIdx_x("show"); if(!point) result=10*result+3; else { result=result+multiple*3; multiple=multiple*0.1; } name.value=String(result); } function onbutton4() { var name=document.getElementByIdx_x("show"); if(!point) result=10*result+4; else { result=result+multiple*4; multiple=multiple*0.1; } name.value=String(result); } function onbutton5() { var name=document.getElementByIdx_x("show"); if(!point) result=10*result+5; else { result=result+multiple*5; multiple=multiple*0.1; } name.value=String(result); } function onbutton6() { var name=document.getElementByIdx_x("show"); if(!point) result=10*result+6; else { result=result+multiple*6; multiple=multiple*0.1; } name.value=String(result); } function onbutton7() { var name=document.getElementByIdx_x("show"); if(!point) result=10*result+7; else { result=result+multiple*7; multiple=multiple*0.1; } name.value=String(result); } function onbutton8() { var name=document.getElementByIdx_x("show"); if(!point) result=10*result+8; else { result=result+multiple*8; multiple=multiple*0.1; } name.value=String(result); } function onbutton9() { var name=document.getElementByIdx_x("show"); if(!point) result=10*result+9; else { result=result+multiple*9; multiple=multiple*0.1; } name.value=String(result); } function onbutton_point() //小数点按钮 { var name=document.getElementByIdx_x("show"); point=true; name.value=String(result)+"."; } function onbutton_back() //退格按钮 { var name=document.getElementByIdx_x("show"); var temp=name.value; name.value=""; for(var i=0;i<temp.length-1;i++) name.value+=temp[i]; } function onbutton_plus() { var name=document.getElementByIdx_x("show"); point=false; multiple=0.1; switch (sort) //遇到下一个操作符时判断上一个操作符是什么，并进行上一个操作符的计算 { //eg:1+2+3= 遇到第二个+时判断前一个符号，发现是+则进行+运算，得到3赋给result case 1:result=result+temp; break; case 2:result=temp-result; break; case 3:result=temp*result; break; case 4:result=temp/result; break; } sort=1; temp=result; result=0; name.value="0"; } function onbutton_minus() { var name=document.getElementByIdx_x("show"); point=false; multiple=0.1; switch (sort) { case 1:result=result+temp; break; case 2:result=temp-result; break; case 3:result=temp*result; break; case 4:result=temp/result; break; } sort=2; temp=result; result=0; name.value="0"; } function onbutton_mult() { var name=document.getElementByIdx_x("show"); point=false; multiple=0.1; switch (sort) { case 1:result=result+temp; break; case 2:result=temp-result; break; case 3:result=temp*result; break; case 4:result=temp/result; break; } sort=3; temp=result; result=0; name.value="0"; } function onbutton_div() { var name=document.getElementByIdx_x("show"); point=false; multiple=0.1; switch (sort) { case 1:result=result+temp; break; case 2:result=temp-result; break; case 3:result=temp*result; break; case 4:result=temp/result; break; } sort=4; temp=result; result=0; name.value="0"; } function onbutton_equal() { var name=document.getElementByIdx_x("show"); point=false; //重置 multiple=0.1; //重置 switch (sort) { case 1:result=result+temp; break; case 2:result=temp-result; break; case 3:result=temp*result; break; case 4:result=temp/result; break; } sort=0; //重置 temp=result; result=0; name.value=String(temp); } function onbutton_clear() //重置为初始状态 { result=0; point=false; multiple=0.1; //初始化小数点后的倍率 sort=0; //标记加减乘除 temp=0; //记录上一轮结果 var name=document.getElementByIdx_x("show"); name.value="0"; } </script></head> <body> <table align="center"> <tr> <td colspan="5"><input type="text" value="0" id="show"></td> </tr> <tr> <td><input type="button" value="7" onclick="onbutton7();"></td> <td><input type="button" value="8" onclick="onbutton8();"></td> <td><input type="button" value="9" onclick="onbutton9();"></td> <td><input type="button" value="/" onclick="onbutton_div();"></td> <td><input type="button" value="<" onclick="onbutton_back();"></td> </tr> <tr> <td><input type="button" value="4" onclick="onbutton4();"></td> <td><input type="button" value="5" onclick="onbutton5();"></td> <td><input type="button" value="6" onclick="onbutton6();"></td> <td><input type="button" value="*" onclick="onbutton_mult();"></td> <td><input type="button" value="C" onclick="onbutton_clear();"></td> </tr> <tr> <td><input type="button" value="1" onclick="onbutton1();"></td> <td><input type="button" value="2" onclick="onbutton2();"></td> <td><input type="button" value="3" onclick="onbutton3();"></td> <td><input type="button" value="-" onclick="onbutton_minus();"></td> <td rowspan="2"><input type="button" value="=" style="width:25px;height:57px;" onclick="onbutton_equal();"></td> </tr> <tr> <td colspan="2"><input type="button" value="0" style="width:57px;height:25px;" onclick="onbutton0();"></td> <td><input type="button" value="." onclick="onbutton_point();"></td> <td><input type="button" value="+" onclick="onbutton_plus();"></td> </tr> </table></body></html>新闻热点
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