February 26, 2015

A simple calculator using JavaScript and CSS3

A simple calculator using JavaScript and CSS3

Make a simple calculator using Javascript and CSS3. There is no images used here. The design of the calculator is done by CSS3. The 3d button effect is done by CSS3 shadows. The smooth press effect of the button is done by CSS3 transitions. Basic regular expression is used for validation and text replacements.

When the number button or operator button is pressed, the value is appended to an equation string displayed on the calculator screen which is later used in the JS eval function to generate the output.

HTML

<div id="calculator">
  <div class="screen"></div>
    <div class="top">
      <span class="clear">C</span>
      <div class="solar"></div>
    </div>
 
    <div class="keys">
        <span>7</span>
        <span>8</span>
        <span>9</span>
        <span class="operator">+</span>
        <span>4</span>
        <span>5</span>
        <span>6</span>
        <span class="operator">-</span>
        <span>1</span>
        <span>2</span>
        <span>3</span>
        <span class="operator">÷</span>
        <span>0</span>
        <span>.</span>
        <span class="eval">=</span>
        <span class="operator">x</span>
    </div>
</div>

CSS


* {
 margin: 0;
 padding: 0;
 box-sizing: border-box;
 font: bold 14px Arial, sans-serif;
}


html {
 height: 100%;
 background: white;
 background: radial-gradient(circle, #fff 20%, #ccc);
 background-size: cover;
}

#calculator {
 width: 325px;
 height: auto;
 margin: 30px auto;
 padding: 20px 20px 9px;
 background: #d94362;
 border-radius: 3px;
 box-shadow: 0px 4px #a23c56, 0px 10px 15px rgba(0, 0, 0, 0.2);
}

.top span.clear {
 float: left;
}

.screen {
 height: 40px;
 width: 212px; 
 float: right; 
 padding: 0 10px; 
 background: rgba(0, 0, 0, 0.2);
 border-radius: 3px;
 box-shadow: inset 0px 4px rgba(0, 0, 0, 0.2);
 font-size: 17px;
 line-height: 40px;
 color: white;
 text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.2);
 text-align: right;
 letter-spacing: 1px;
}

.keys, .top {overflow: hidden}

.keys span, .top span.clear {
 float: left;
 position: relative;
 top: 0; 
 cursor: pointer; 
 width: 66px;
 height: 36px; 
 background: white;
 border-radius: 3px;
 box-shadow: 0px 4px rgba(0, 0, 0, 0.2); 
 margin: 0 7px 11px 0; 
 color: #333;
 line-height: 36px;
 text-align: center;
 user-select: none;
 transition: all 0.2s ease;
}

.keys span.operator {
 background: #FFF0F5;
 margin-right: 0;
}

.keys span.eval {
 background: #c6ce9e;
 box-shadow: 0px 4px #89925e;
 color: #222;
}

.top span.clear {
 background: #c6ce9e;
 box-shadow: 0px 4px #89925e;
 color: 888;
}

.keys span:hover {
 background: #4f3043;
 box-shadow: 0px 4px #6b54d3;
 color: white;
}

.keys span.eval:hover {
 background: #abb850;
 box-shadow: 0px 4px #717a33;
 color: #ffffff;
}

.top span.clear:hover {
 background: #abb850;
 box-shadow: 0px 4px #717a33;
 color: white;
}

.keys span:active {
 box-shadow: 0px 0px #6b54d3;
 top: 4px;
}

.keys span.eval:active {
 box-shadow: 0px 0px #717a33;
 top: 4px;
}

.top span.clear:active {
 top: 4px;
 box-shadow: 0px 0px #d3545d;
}

JavaScript

var keys = document.querySelectorAll('#calculator span');
var operators = ['+', '-', 'x', '÷'];
var decimalAdded = false;


for(var i = 0; i < keys.length; i++) {
 keys[i].onclick = function(e) {
  var input = document.querySelector('.screen');
  var inputVal = input.innerHTML;
  var btnVal = this.innerHTML;
  
  if(btnVal == 'C') {
   input.innerHTML = '';
   decimalAdded = false;
  } else if(btnVal == '=') {
   var equation = inputVal;
   var lastChar = equation[equation.length - 1];
   equation = equation.replace(/x/g, '*').replace(/÷/g, '/');
   
   // Final thing left to do is checking the last character of the equation. If it's an operator or a decimal, remove it
   if(operators.indexOf(lastChar) > -1 || lastChar == '.')
    equation = equation.replace(/.$/, '');
   
   if(equation)
    input.innerHTML = eval(equation);
    
   decimalAdded = false;
  } else if(operators.indexOf(btnVal) > -1) {
   var lastChar = inputVal[inputVal.length - 1];
   if(inputVal != '' && operators.indexOf(lastChar) == -1) 
    input.innerHTML += btnVal;
   
   else if(inputVal == '' && btnVal == '-') 
    input.innerHTML += btnVal;
   
   if(operators.indexOf(lastChar) > -1 && inputVal.length > 1) {
    // Here, '.' matches any character while $ denotes the end of string, so anything (will be an operator in this case) at the end of string will get replaced by new operator
    input.innerHTML = inputVal.replace(/.$/, btnVal);
   }
   
   decimalAdded =false;
  }
  else if(btnVal == '.') {
   if(!decimalAdded) {
    input.innerHTML += btnVal;
    decimalAdded = true;
   }
  } else {
   input.innerHTML += btnVal;
  }
  e.preventDefault();
 } 
}
demo

No comments:

Post a Comment

Popular Posts

Views