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<div id="app"></div>
html, body {
background-color: #1D1E22;
color: #fff;
font-family: 'Roboto', sans-serif;
font-size: 24px;
height: 100%;
margin: 0;
width: 100%;
}
#app {
align-items: center;
display: flex;
justify-content: center;
height: 100%;
}
#calc {
background-color: rgba(255, 255, 255, .05);
border-radius: 2px;
padding: 15px;
}
#display {
background-color: rgba(255, 255, 255, 0.1);
border-radius: 2px;
padding: 30px;
margin-bottom: 15px;
min-height: 27px;
text-align: right;
}
#buttons {
display: grid;
grid-template-columns: 1fr 1fr 1fr 1fr;
}
#buttons button {
align-items: center;
background-color: rgba(255, 255, 255, 0.29);
border: none;
border-radius: 2px;
cursor: pointer;
display: flex;
justify-content: center;
padding: 30px 35px;
margin: 4px;
outline: none;
}
.primaryBtn {
background-color: rgba(255, 255, 255, 0.5) !important;
}
const App = () => (
<Calc />
)
class Calc extends React.Component {
state = {
display: '0',
expression: [],
currentNum: '0'
}
handleClickButton = e => {
switch (e.target.id) {
case 'clear':
this.clearDisplay()
break
case 'divide':
this.handleOperation('/')
break
case 'multiply':
this.handleOperation('*')
break
case 'seven':
this.handleNumber(7)
break
case 'eight':
this.handleNumber(8)
break
case 'nine':
this.handleNumber(9)
break
case 'subtract':
this.handleOperation('-')
break
case 'four':
this.handleNumber(4)
break
case 'five':
this.handleNumber(5)
break
case 'six':
this.handleNumber(6)
break
case 'add':
this.handleOperation('+')
break
case 'one':
this.handleNumber(1)
break
case 'two':
this.handleNumber(2)
break
case 'three':
this.handleNumber(3)
break
case 'equals':
this.handleCalc()
break
case 'zero':
this.handleNumber(0)
break
case 'decimal':
this.handleDecimal()
break
}
}
clearDisplay = () => {
this.setState(() => ({
display: '0',
expression: [],
currentNum: '0',
prevCalc: undefined
}))
}
handleNumber = num => {
const { prevCalc } = this.state
if (prevCalc !== undefined) {
this.setState(prevState => {
return {
display: num.toString(),
expression: [],
currentNum: num.toString(),
prevCalc: undefined
}
})
} else {
this.setState(prevState => {
const { display, expression, currentNum } = prevState
return {
display: display === '0' ? num.toString() : display + num.toString(),
currentNum: currentNum === '0' ? num.toString() : currentNum + num.toString()
}
})
}
}
handleDecimal = () => {
this.setState(prevState => {
const { display, expression, currentNum } = prevState
const update = currentNum.indexOf('.') > -1
return {
display: update ? display : display + '.',
currentNum: update ? currentNum : currentNum + '.',
prevCalc: undefined
}
})
}
handleOperation = op => {
const { expression, currentNum } = this.state
if (currentNum === '') {
this.setState(prevState => {
const { expression, currentNum } = prevState
let newExpression = [...expression]
newExpression.splice(-1, 1)
return {
expression: newExpression.concat([op]),
currentNum: '',
prevCalc: undefined
}
})
this.updateDisplay()
} else {
this.setState(prevState => {
const { display, expression, currentNum } = prevState
return {
expression: expression.concat([currentNum]).concat([op]),
currentNum: '',
prevCalc: undefined
}
})
this.updateDisplay()
}
}
updateDisplay = () => {
this.setState(prevState => {
const { expression, currentNum } = prevState
return {
display: expression.join('')
}
})
}
handleCalc = () => {
const { display } = this.state
if (!/[*/+-]/.test(display.charAt(display.length - 1))) {
this.setState(prevState => {
const { display, expression, currentNum } = prevState
return {
display: eval(this.state.expression.join('') + this.state.currentNum).toString(),
expression: [],
currentNum: eval(this.state.expression.join('') + this.state.currentNum).toString(),
prevCalc: eval(this.state.expression.join('') + this.state.currentNum).toString()
}
})
}
}
render () {
return (
<div id='calc'>
<Display display={this.state.display.substring(0, 23)} />
<div id='buttons'>
<button id='clear' style={{ gridColumnStart: 1, gridColumnEnd: 3 }} onClick={this.handleClickButton}>AC</button>
<button id='divide' onClick={this.handleClickButton}>/</button>
<button id='multiply' onClick={this.handleClickButton}>x</button>
<button id='seven' className='primaryBtn' onClick={this.handleClickButton}>7</button>
<button id='eight' className='primaryBtn' onClick={this.handleClickButton}>8</button>
<button id='nine' className='primaryBtn' onClick={this.handleClickButton}>9</button>
<button id='subtract' onClick={this.handleClickButton}>-</button>
<button id='four' className='primaryBtn' onClick={this.handleClickButton}>4</button>
<button id='five' className='primaryBtn' onClick={this.handleClickButton}>5</button>
<button id='six' className='primaryBtn' onClick={this.handleClickButton}>6</button>
<button id='add' onClick={this.handleClickButton}>+</button>
<button id='one' className='primaryBtn' onClick={this.handleClickButton}>1</button>
<button id='two' className='primaryBtn' onClick={this.handleClickButton}>2</button>
<button id='three' className='primaryBtn' onClick={this.handleClickButton}>3</button>
<button id='equals' style={{ gridColumnStart: 4, gridRowStart: 4, gridRowEnd: 6 }} onClick={this.handleClickButton}>=</button>
<button id='zero' style={{ gridColumnStart: 1, gridColumnEnd: 3 }} onClick={this.handleClickButton}>0</button>
<button id='decimal' style={{ }} onClick={this.handleClickButton}>.</button>
</div>
</div>
)
}
}
const Display = props => (
<div id="display">{props.display}</div>
)
ReactDOM.render(<Calc />, document.getElementById('app'))
Also see: Tab Triggers