Membuat Kalkulator dengan javascript

Membuat Kalkulator dengan javascript.

Pada tutorial kali ini kita akan membuat kalulator sederhana dengan javascript.

• Buat javascript seperti ini

 <script>  
 function addChar(input, character) {  
      if(input.value == null || input.value == "0")  
           input.value = character  
      else  
           input.value += character  
 }  
 function cos(form) {  
      form.display.value = Math.cos(form.display.value);  
 }  
 function sin(form) {  
      form.display.value = Math.sin(form.display.value);  
 }  
 function tan(form) {  
      form.display.value = Math.tan(form.display.value);  
 }  
 function sqrt(form) {  
      form.display.value = Math.sqrt(form.display.value);  
 }  
 function ln(form) {  
      form.display.value = Math.log(form.display.value);  
 }  
 function exp(form) {  
      form.display.value = Math.exp(form.display.value);  
 }  
 function deleteChar(input) {  
      input.value = input.value.substring(0, input.value.length - 1)  
 }  
 function changeSign(input) {  
      if(input.value.substring(0, 1) == "-")  
           input.value = input.value.substring(1, input.value.length)  
      else  
           input.value = "-" + input.value  
 }  
 function compute(form) {  
      form.display.value = eval(form.display.value)  
 }  
 function square(form) {  
      form.display.value = eval(form.display.value) * eval(form.display.value)  
 }  
 function checkNum(str) {  
      for (var i = 0; i < str.length; i++) {  
           var ch = str.substring(i, i+1)  
           if (ch < "0" || ch > "9") {  
                if (ch != "/" && ch != "*" && ch != "+" && ch != "-" && ch != "."  
                     && ch != "(" && ch!= ")") {  
                     alert("invalid entry!")  
                     return false  
                     }  
                }  
           }  
           return true  
 }  
 </script>  

• Code  css

 form{  
      width:440px;  
      padding:25px;  
      margin:auto;  
      border:5px solid #aaa;  
      border-radius:15px 15px;  
      }  
      input{  
      background:#888;  
      color:#fff;  
      font-size:15px;  
      padding-top:15px;  
      padding-bottom:15px;  
      padding-left:19px;  
      padding-right:19px;  
      margin:6px;  
      }  
      h2{  
      text-align:center;  
      }  
      .sc{  
      background:#fff;  
      color:#000;  
      }  

• Buat form (html)

 <form name="sci-calc">  
 <h2>SCIENTIFIC CALCULATOR</h2>  
 <table cellspacing="0" cellpadding="1">  
 <TR>  
 <TD COLSPAN="5" ALIGN="center"><input NAME="display" class="sc" VALUE="0" SIZE="44" MAXLENGTH="25"></TD>  
 </TR>  
 <TR>                   
 <td align="center"><input type="button" value="Clear" ONCLICK="this.form.display.value = 0 "></TD>  
 <td align="center" colspan="2"><input type="button" value="   Backspace   " ONCLICK="deleteChar(this.form.display)"></TD>  
 <td align="center" colspan="2"><input type="button" value="      Enter     " NAME="Enter" ONCLICK="if (checkNum(this.form.display.value)) { compute(this.form) }"></TD>  
 </TR>   
 <TR>  
 <td align="center"><input type="button" value=" exp " ONCLICK="if (checkNum(this.form.display.value)) { exp(this.form) }"></TD>  
 <td align="center"><input type="button" value=" 7 " ONCLICK="addChar(this.form.display, '7')"></TD>  
 <td align="center"><input type="button" value=" 8 " ONCLICK="addChar(this.form.display, '8')"></TD>  
 <td align="center"><input type="button" value=" 9 " ONCLICK="addChar(this.form.display, '9')"></TD>  
 <td align="center"><input type="button" value="  /  " ONCLICK="addChar(this.form.display, '/')"></TD>  
 </TR>                   
 <TR>                    
 <td align="center"><input type="button" value=" ln  " ONCLICK="if (checkNum(this.form.display.value)) { ln(this.form) }"></TD>  
 <td align="center"><input type="button" value=" 4 " ONCLICK="addChar(this.form.display, '4')"></TD>  
 <td align="center"><input type="button" value=" 5 " ONCLICK="addChar(this.form.display, '5')"></TD>  
 <td align="center"><input type="button" value=" 6 " ONCLICK="addChar(this.form.display, '6')"></TD>  
 <td align="center"><input type="button" value="  *  " ONCLICK="addChar(this.form.display, '*')"></TD>  
 </TR>                    
 <TR>                    
 <td align="center"><input type="button" value=" sqrt " ONCLICK="if (checkNum(this.form.display.value)) { sqrt(this.form) }"></TD>  
 <td align="center"><input type="button" value=" 1 " ONCLICK="addChar(this.form.display, '1')"></TD>  
 <td align="center"><input type="button" value=" 2 " ONCLICK="addChar(this.form.display, '2')"></TD>  
 <td align="center"><input type="button" value=" 3 " ONCLICK="addChar(this.form.display, '3')"></TD>  
 <td align="center"><input type="button" value="  -  " ONCLICK="addChar(this.form.display, '-')"></TD>  
 </TR>                   
 <TR>                    
 <td align="center"><input type="button" value=" sq " ONCLICK="if (checkNum(this.form.display.value)) { square(this.form) }"></TD>  
 <td align="center"><input type="button" value=" 0 " ONCLICK="addChar(this.form.display, '0')"></TD>  
 <td align="center"><input type="button" value="  . " ONCLICK="addChar(this.form.display, '.')"></TD>  
 <td align="center"><input type="button" value=" +/- " ONCLICK="changeSign(this.form.display)"></TD>  
 <td align="center"><input type="button" value="  + " ONCLICK="addChar(this.form.display, '+')"></TD>  
 </TR>                   
 <TR>                    
 <td align="center"><input type="button" value="  (  " ONCLICK="addChar(this.form.display, '(')"></TD>  
 <td align="center"><input type="button" value="cos" ONCLICK="if (checkNum(this.form.display.value)) { cos(this.form) }"></TD>  
 <td align="center"><input type="button" value=" sin " ONCLICK="if (checkNum(this.form.display.value)) { sin(this.form) }"></TD>  
 <td align="center"><input type="button" value=" tan" ONCLICK="if (checkNum(this.form.display.value)) { tan(this.form) }"></TD>  
 <td align="center"><input type="button" value="  )  " ONCLICK="addChar(this.form.display, ')')"></TD>  
 </TR>                   
 </table>  
 </form>  

Semoga berhasil.