Source code simple calculator from WebDevSimplified
Here are the Youtube link https://youtu.be/j59qQ7YWLxw?si=SQWMUCxT5xfAcfjW
Create a folder for the project, example: simple-calculator
Create three file for HTML, CSS, and Javascript.
HTML Source Code
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<!-- 1. Add title of the webpage -->
<title>Calculator</title>
<!-- 2. Link to CSS File -->
<link href="style.css" rel="stylesheet">
<!-- 3. Link to Javascript File -->
<script src="app.js" defer></script>
</head>
<body>
<!-- 4. Create div with class "calculator-grid" for display output and result of calculation -->
<div class="calculator-grid">
<div class="output">
<div data-previous-operand class="previous-operand"></div>
<div data-current-operand class="current-operand"></div>
</div>
<!-- 5. Create button for basic calculation -->
<button data-all-clear class="span-two">AC</button>
<button data-delete>DEL</button>
<button data-operation>÷</button>
<button data-number>1</button>
<button data-number>2</button>
<button data-number>3</button>
<button data-operation>*</button>
<button data-number>4</button>
<button data-number>5</button>
<button data-number>6</button>
<button data-operation>+</button>
<button data-number>7</button>
<button data-number>8</button>
<button data-number>9</button>
<button data-operation>-</button>
<button data-number>.</button>
<button data-number>0</button>
<button data-equals class="span-two">=</button>
</div>
</body>
</html>
CSS Source Code
*, *::before, *::after {
box-sizing: border-box;
font-family: Gotham Rounded, sans-serif;
font-weight: normal;
}
body {
padding: 0;
margin: 0;
background: linear-gradient(to right, #00AAFF, #00FF6C);
}
.calculator-grid {
display: grid;
justify-content: center;
align-content: center;
min-height: 100vh;
grid-template-columns: repeat(4, 100px);
grid-template-rows: minmax(120px, auto) repeat(5, 100px);
}
.calculator-grid > button {
cursor: pointer;
font-size: 2rem;
border: 1px solid white;
outline: none;
background-color: rgba(255, 255, 255, .75);
}
.calculator-grid > button:hover {
background-color: rgba(255, 255, 255, .9);
}
.span-two {
grid-column: span 2;
}
.output {
grid-column: 1 / -1;
background-color: rgba(0, 0, 0, .75);
display: flex;
align-items: flex-end;
justify-content: space-around;
flex-direction: column;
padding: 10px;
word-wrap: break-word;
word-break: break-all;
}
.output .previous-operand {
color: rgba(255, 255, 255, .75);
font-size: 1.5rem;
}
.output .current-operand {
color: white;
font-size: 2.5rem;
}
Javascript Source Code
class Calculator {
constructor(previousOperandTextElement, currentOperandTextElement) {
// Initialize the calculator with the previous and current operand text elements
this.previousOperandTextElement = previousOperandTextElement
this.currentOperandTextElement = currentOperandTextElement
this.clear() // Call the clear method to reset the calculator
}
clear() {
// Clear the current and previous operands and set the operation to undefined
this.currentOperand = ''
this.previousOperand = ''
this.operation = undefined
}
delete() {
// Delete the last character of the current operand
this.currentOperand = this.currentOperand.toString().slice(0, -1)
}
appendNumber(number) {
// Append the selected number to the current operand, unless it already contains a decimal point
if (number === '.' && this.currentOperand.includes('.')) return
this.currentOperand = this.currentOperand.toString() + number.toString()
}
chooseOperation(operation) {
// Choose the operation to be performed
if (this.currentOperand === '') return // If there is no current operand, return
if (this.previousOperand !== '') {
this.compute() // If there is a previous operand, compute the result
}
this.operation = operation // set the operation
this.previousOperand = this.currentOperand // Set the previous operand to the current operand
this.currentOperand = '' // Clear the current operand
}
compute() {
// Perform the computation based on the chosen operation
let computation
const prev = parseFloat(this.previousOperand)
const current = parseFloat(this.currentOperand)
if (isNaN(prev) || isNaN(current)) return // If either operand is not a number, return
switch (this.operation) {
case '+':
computation = prev + current
break
case '-':
computation = prev - current
break
case '*':
computation = prev * current
break
case '÷':
computation = prev / current
break
default:
return
}
this.currentOperand = computation // Set the current operand to the computed value
this.operation = undefined // Reset the operation
this.previousOperand = '' // Clear the previous operand
}
getDisplayNumber(number) {
// Format the number to be displayed on the calculator screen
const stringNumber = number.toString()
const integerDigits = parseFloat(stringNumber.split('.')[0])
const decimalDigits = stringNumber.split('.')[1]
let integerDisplay
if (isNaN(integerDigits)) {
integerDisplay = ''
} else {
integerDisplay = integerDigits.toLocaleString('en', { maximumFractionDigits: 0 })
}
if (decimalDigits != null) {
return `${integerDisplay}.${decimalDigits}`
} else {
return integerDisplay
}
}
updateDisplay() {
// Update the calculator screen with the current and previous operands
this.currentOperandTextElement.innerText =
this.getDisplayNumber(this.currentOperand)
if (this.operation != null) {
this.previousOperandTextElement.innerText =
`${this.getDisplayNumber(this.previousOperand)} ${this.operation}`
} else {
this.previousOperandTextElement.innerText = ''
}
}
}
const numberButtons = document.querySelectorAll('[data-number]')
const operationButtons = document.querySelectorAll('[data-operation]')
const equalsButton = document.querySelector('[data-equals]')
const deleteButton = document.querySelector('[data-delete]')
const allClearButton = document.querySelector('[data-all-clear]')
const previousOperandTextElement = document.querySelector('[data-previous-operand]')
const currentOperandTextElement = document.querySelector('[data-current-operand]')
const calculator = new Calculator(previousOperandTextElement, currentOperandTextElement)
numberButtons.forEach(button => {
button.addEventListener('click', () => {
calculator.appendNumber(button.innerText)
calculator.updateDisplay()
})
})
operationButtons.forEach(button => {
button.addEventListener('click', () => {
calculator.chooseOperation(button.innerText)
calculator.updateDisplay()
})
})
equalsButton.addEventListener('click', button => {
calculator.compute()
calculator.updateDisplay()
})
allClearButton.addEventListener('click', button => {
calculator.clear()
calculator.updateDisplay()
})
deleteButton.addEventListener('click', button => {
calculator.delete()
calculator.updateDisplay()
})
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