JavaScript实现科学计算器运⾏效果：
可实现科学计算器的功能，如：PI，sin，cos，tan等
源代码：
1 <!DOCTYPE html>
2 <html lang="zh">
3
4 <head>
5 <meta charset="UTF-8">
6 <title>计算器练习</title>
7 <style type="text/css">
8 table {
9 margin: 15px auto;
10 font-size: 22px;
11 border: 5px outset orange;
12
13 }
14
15 #tab-1,
16 #tab-2,
17 #tab-3 {
18 border: 3px outset rgba(15, 10, 10, 0.3);
19 }
20
21 input {
22 outline: none;
23 box-shadow: 5px 5px 2px rgba(100, 100, 100, 0.8) inset;
24 }
25
26 #txtnum {
27 text-align: right;
28 height: 50px;
29 width: 100%;
30 background: #fff;
31 font-size: 22px;
32 }
33
34 td {
35 padding: 5px;
36 background: #ccc;
37
38 }
39
40 [type=button] {
41 width: 60px;
42 height: 40px;
43 border-radius: 5px;
44 background: #fff;
45 box-shadow: 5px 3px 2px rgba(100, 100, 100, 0.6) inset;
46 }
47 </style>
48 </head>
49
50 <body>
51 <!-- 主表设计 -->
52 <table id="main" cellspacing="0">
53 <!-- (tr>td*3)*2 快捷⽅式-->
54 <tr>
55 <td colspan="2">
56 <input type="text" id="txtnum" value="0">
57 </td>
58 <td>
59 <table id="tab-1">
60 <tr>
61 <td><input type="button" id="cc" value="清除" onclick="txtnum.value='0';result=0 "></td>
62 <td><input type="button" id="tg" value="退格" onclick="backspace()"></td>
63 </tr>
64 </table>
65 </td>
66 </tr>
67 <tr>
68 <td>
69 <table id="tab-2">
70 <!-- (tr>(td>input)*3)*4 -->
71 <tr>
72 <td><input type="button" id="sin" value="sin" onclick="math('sin')"></td>
73 <td><input type="button" id="cos" value="cos" onclick="math('cos')"></td>
74 <td><input type="button" id="tan" value="tan" onclick="math('tan')"></td>
75 </tr>
76 <tr>
77 <td><input type="button" id="asin" value="asin" onclick="math('asin')"></td>
78 <td><input type="button" id="acon" value="acon" onclick="math('acon')"></td>
79 <td><input type="button" id="atan" value="atan" onclick="math('atan')"></td>
80 </tr>
81 <tr>
82 <td><input type="button" id="PI" value="PI" onclick="math('PI')"></td>
83 <td><input type="button" value="1/x" onclick="math('1/x')"></td>
84 <td><input type="button" value="e" onclick="math('e')"></td>
85 </tr>
86 <tr>
87 <td><input type="button" value="lnx" onclick="math('lnx')"></td>
88 <td><input type="button" value="lgx" onclick="math('lgx')"></td>
89 <td><input type="button" value="sqrt" onclick="math('sqrt')"></td>
90 </tr>
91 </table>
92 </td>
93 <td>
94 <table id="tab-3">
95 <!-- (tr>(td>input)*3)*4 -->
96 <tr>
97 <td><input type="button" id="" value="7" onclick="num('7')"></td>
98 <td><input type="button" id="" value="8" onclick="num('8')"></td>
99 <td><input type="button" id="" value="9" onclick="num('9')"></td>
100 </tr>
101 <tr>
102 <td><input type="button" id="" value="4" onclick="num('4')"></td>
103 <td><input type="button" id="" value="5" onclick="num('5')"></td>
104 <td><input type="button" id="" value="6" onclick="num('6')"></td>
105 </tr>
106 <tr>
107 <td><input type="button" id="" value="1" onclick="num('1')"></td>
108 <td><input type="button" value="2" onclick="num('2')"></td>
109 <td><input type="button" value="3" onclick="num('3')"></td>
110 </tr>
111 <tr>
112 <td><input type="button" value="0" onclick="num('0')"></td>
113 <td><input type="button" value="." onclick="decimal()"></td>
114 <td><input type="button" value="=" onclick="compute('=')"></td>
115 </tr>
116 </table>
117 </td>
118 <td>
119 <table id="tab-3">
120 <tr>
121 <td><input type="button" id="" value="+" onclick="compute('+')"></td>
122 <td><input type="button" id="" value="取整" onclick="math('i')"></td>
123 </tr>
124 <tr>
125 <td><input type="button" id="" value="-" onclick="compute('-')"></td>
126 <td><input type="button" id="" value="取余" onclick="compute('%')"></td>
127 </tr>
128 <tr>
129 <td><input type="button" id="" value="*" onclick="compute('*')"></td>
130 <td><input type="button" id="" value="x^y" onclick="compute('x^y')"></td>
131 </tr>
132 <tr>
133 <td><input type="button" id="" value="/" onclick="compute('/')"></td> 134 <td><input type="button" id="" value="+/-" onclick="reverse()"></td> 135 </tr>
136 </table>
137 </td>
138 </tr>
139 </table>
140 <script type="text/javascript">
141//operator 运算符
142var Boo = false; //判断是否按下计算符号的布尔变量；
143var result = 0; //存储计算数据的变量
144var ope; //存储计算符号的变量
145
146function $(x) {
ElementById(x);
148 }
149
150function decimal() {
151var txt = $('txtnum');
152if (Boo) {
153 txt.value = '0.'; //若接受过运算符，⽂本框清零
154 } else {
155if (txt.value.indexOf('.') == -1) { //判断数值中是否已经有⼩数点
156 txt.value += '.'; //若没有则加上
157 }
158 }
159 Boo = false; //若接受过运算符，⽂本框不能清零
160 }
161//indexOf() ⽅法可返回某个指定的字符串值在字符串中⾸次出现的位置。
162//如果要检索的字符串值没有出现，则该⽅法返回 -1。
163
164function num(Num) {
165var txt = $('txtnum');
166if (Boo) {
167 txt.value = Num;
javascript计算器代码168 Boo = false;
169 } else {
170if (txt.value == '0') {
171 txt.value = Num;
172 } else {
173 txt.value += Num;
174 }
175 }
176 }
177
178function compute(op) {
179var onum = $('txtnum').value;
180if (onum == '') { onum = 0; }
181 Boo = true;
182switch (ope) {
183case '+':
184 result += parseFloat(onum); break;
185case '-':
186 result -= parseFloat(onum); break;
187case '*':
188 result *= parseFloat(onum); break;
189case '/':
190 result /= parseFloat(onum); break;
191case '=':
192 result = parseFloat(onum); break;
193case '%':
194 result %= onum; break;
195//{result%=onum;break;}break;
196case 'x^y':
197 result = Math.pow(result, onum); break;
198//{result=Math.pow(result,onum);break;}break;
199default: result = parseFloat(onum); break;
200 }
201 $('txtnum').value = result;
202 ope = op;
203
204 }
205
206function math(op) {
207var onum = $('txtnum').value;
208if (onum == '') { alert('数据不能为空'); };
209 Boo = true;
210with (Math) {
211switch (op) {
212case 'sin': result = sin(onum); break;
213case 'cos': result = cos(onum); break;
214case 'tan': result = tan(onum); break;
215case 'asin': result = asin(onum); break;
216case 'acos': result = acos(onum); break;
217case 'atan': result = atan(onum); break;
218case 'PI': result = PI; break;
219case '1/x': result = 1 / onum; break;
220case 'e': result = E; break;
221case 'lnx': result = log(onum); break;
222case 'lgx': result = log(onum) / log(10); break; 223
224case 'i': result = floor(onum); break;
225
226case 'sqrt': result = jc(onum); break;
227default: result = parseFloat(onum); break;
228 }
229 }
230 $('txtnum').value = result;
231 }
232
233function jc(a) {
234return Math.sqrt(a);
235 }
236
237function reverse() {
238var Num1 = $('txtnum').value;
239if (Num1 == '') {
240 alert('数据不能为空');
241 } else {
242 $('txtnum').value *= -1;
243 }
244
245 }
246
247function backspace() {
248var txt = $('txtnum');
249 txt.value = txt.value.substring(0, txt.value.length - 1); 250if (txt.value == '') { txt.value = 0; }
251 }
252 </script>
253 </body>
254
255 </html>
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