Kalkulator

Kalkulator dengan Javascript dan CSS3

by MAz Mawan

HTML

<div id="calculator">
	<!-- Screen and clear key -->
	<div class="top">
		<span class="clear">C</span>
		<div class="screen"></div>
	</div>
	
	<div class="keys">
		<!-- operators and other 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>

<!-- PrefixFree -->
<script src="http://thecodeplayer.com/uploads/js/prefixfree-1.0.7.js" type="text/javascript" type="text/javascript"></script>

CSS

/* Basic reset */
* {
	margin: 0;
	padding: 0;
	box-sizing: border-box;
	
	/* Better text styling */
	font: bold 14px Arial, sans-serif;
}

/* Finally adding some IE9 fallbacks for gradients to finish things up */

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

/* Using box shadows to create 3D effects */
#calculator {
	width: 325px;
	height: auto;
	
	margin: 100px auto;
	padding: 20px 20px 9px;
	
	background: #9dd2ea;
	background: linear-gradient(#9dd2ea, #8bceec);
	border-radius: 3px;
	box-shadow: 0px 4px #009de4, 0px 10px 15px rgba(0, 0, 0, 0.2);
}

/* Top portion */
.top span.clear {
	float: left;
}

/* Inset shadow on the screen to create indent */
.top .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);
	
	/* Typography */
	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;
}

/* Clear floats */
.keys, .top {overflow: hidden;}

/* Applying same to the keys */
.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: #888;
	line-height: 36px;
	text-align: center;
	
	/* prevent selection of text inside keys */
	user-select: none;
	
	/* Smoothing out hover and active states using css3 transitions */
	transition: all 0.2s ease;
}

/* Remove right margins from operator keys */
/* style different type of keys (operators/evaluate/clear) differently */
.keys span.operator {
	background: #FFF0F5;
	margin-right: 0;
}

.keys span.eval {
	background: #f1ff92;
	box-shadow: 0px 4px #9da853;
	color: #888e5f;
}

.top span.clear {
	background: #ff9fa8;
	box-shadow: 0px 4px...

JavaScript

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

// Add onclick event to all the keys and perform operations
for(var i = 0; i < keys.length; i++) {
	keys[i].onclick = function(e) {
		// Get the input and button values
		var input = document.querySelector('.screen');
		var inputVal = input.innerHTML;
		var btnVal = this.innerHTML;
		
		// Now, just append the key values (btnValue) to the input string and finally use javascript's eval function to get the result
		// If clear key is pressed, erase everything
		if(btnVal == 'C') {
			input.innerHTML = '';
			decimalAdded = false;
		}
		
		// If eval key is pressed, calculate and display the result
		else if(btnVal == '=') {
			var equation = inputVal;
			var lastChar = equation[equation.length - 1];
			
			// Replace all instances of x and ÷ with * and / respectively. This can be done easily using regex and the 'g' tag which will replace all instances of the matched character/substring
			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;
		}
		
		// Basic functionality of the calculator is complete. But there are some problems like 
		// 1. No two operators should be added consecutively.
		// 2. The equation shouldn't start from an operator except minus
		// 3. not more than 1 decimal should be there in a number
		
		// We'll fix these issues using some simple checks
		
		// indexOf works only in IE9+
		else if(operators.indexOf(btnVal) > -1) {
			// Operator is clicked
			// Get the last character from the equation
			var lastChar = inputVal[inputVal.length - 1];
			
			// Only add operator...