HTML+CSS+JS实现计算机功能（二）

1. 
2. <button onclick="back1()">BK
      </button>
      <button onclick="clearerr()">CE
      </button>
      <button onclick="clear1()">C
      </button>
      <button onclick="inputStr('(')">(
      </button>
      <button onclick="inputStr(')')">)
      </button>
      <br>
3. <button onclick="inputStr(7)">7
      </button>
      <button onclick="inputStr(8)" >8
      </button>
      <button onclick="inputStr(9)">9
      </button>
      <button onclick="inputStr('*')">*
      </button>
      <button onclick="inputStr('/')">/
      </button>
      <br>
4. <button onclick="inputStr(4)">4
      </button>
      <button onclick="inputStr(5)">5
      </button>
      <button onclick="inputStr(6)">6
      </button>
      <button onclick=inputStr('%')>%
      </button>
      <button onclick="reciprocal()">1/x
      </button>
      <br>
5. <button onclick="inputStr(1)">1
      </button>
      <button onclick="inputStr(2)">2
      </button>
      <button onclick="inputStr(3)">3
      </button>
      <button onclick="inputStr('-')">-
      </button>
6. <button onclick="inputStr(0)">0
      </button>
      <button onclick="inputStr('.')">.
      </button>
      <button onclick="inputStr('+')">+
      </button>
7. <button onclick="equal()">=
      </button>
• 1

1. 
      <script>
2. window.οnlοad=
      function(){
3. // 初始化内容
4. var res = 
      eval(
      "(1+4)*2");
5. console.log(res); 
6. //打印进行测试
7. 
          }
8. 
      </script>
• 1

1. 
       <input id=
      "cin" 
      class=
      "input">
2. 
3. 
4. 
5. <script>
6. function inputStr(c) {
7. var cin = 
      document.getElementById(
      "cin");
8. var val = cin.value + c;
9. 
              cin.value = val;
10. 
          }
11. </script>
• 1

1. function equal() {
2. var cin = 
      document.getElementById(
      "cin");
3. var val = cin.value;
4. var res = 
      eval(val);
5. 
              cin.value = res;
6. 
          }
• 1

1. function clear1() {
2. var cin = 
      document.getElementById(
      "cin");
3. 
              cin.value = 
      "";
4. // if(cin.value.length>0){
5. //     document.getElementById("cin").value = "";
6. // }
7. 
          }
8. function back1() {
9. var cin = 
      document.getElementById(
      "cin");
10. 
              cin.value = cin.value.substr(
      0,cin.value.length 
      -1);
11. 
          }
12. function clearerr() {
13. var cin = 
      document.getElementById(
      "cin");
14. var val = cin.value;
15. var index = val.lastIndexOf(
      "-");
16. if(index===
      -1){
17. 
                  index = val.lastIndexOf(
      "+");
18. 
              }
19. if(index===
      -1){
20. 
                  index = val.lastIndexOf(
      "*");
21. 
              }
22. if(index===
      -1){
23. 
                  index = val.lastIndexOf(
      "/");
24. 
              }
25. if(index!==
      -1){
26. 
                  val = val.substring(
      0,index+
      1);
27. 
              }
28. 
29. 
              cin.value = val;
30. 
          }
• 1

1. function reciprocal() {
2. var cin = 
      document.getElementById(
      "cin");
3. var rst = 
      1/cin.value;
4. 
              cin.value = rst;
5. 
          }
• 1