/
calc.js
148 lines (136 loc) · 3.9 KB
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calc.js
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function add(num1,num2) {
return Number(num1) + Number(num2);
}
function subtract(num1,num2) {
return Number(num1) - Number(num2);
}
function multiply(num1,num2) {
return Number(num1) * Number(num2);
}
function divide(num1,num2) {
if (num2==='0') {
alert("Divide by zero not allowed");
numberOne = numberTwo = 0;
firstOperation = true;
return 0;
} else {
return Number(num1) / Number(num2);
}
}
function operate(num1, num2, opt) {
let result=0;
lastKeyIsANumber = false;
task = task==='Enter'? '=': task;
switch (opt) {
case '+':
result = add(num1,num2);
break;
case '-':
result = subtract(num1,num2);
break;
case '*':
result = multiply(num1,num2);
break;
case '/':
result = divide(num1,num2);
break;
case '=':
result = numberOne;
break;
default:
result = 0;
}
numberOne = result;
numDisplay.value = result;
}
function setNumber(num) {
if(clearDisplay) {
numDisplay.value = '';
}
if(num==='') {
numDisplay.value='';
} else {
if (num === '.') {
if (numDisplay.value.match(/\./g)===null) {
numDisplay.value=numDisplay.value+num;
}
}
else if (numDisplay.value==='0') {
numDisplay.value=num;
} else {
numDisplay.value=numDisplay.value+num;
}
}
clearDisplay = false;
}
const numDisplay=document.getElementById('numValue');
const numButton=document.getElementsByClassName('numButton');
const operButton=document.getElementsByClassName('operButton');
let numberOne=0;
let numberTwo=0;
let task;
let firstOperation=true;
let clearDisplay=false;
let lastKeyIsANumber=false;
for (let i=0;i<numButton.length;i++) {
numButton[i].addEventListener('click',function (e) {
setNumber(e.target.value);
lastKeyIsANumber = true;
});
}
for (let i=0;i<operButton.length;i++) {
operButton[i].addEventListener('click',function (e) {
if (e.target.value==='C') {
numDisplay.value = '0';
numberOne = numberTwo = 0;
firstOperation = true;
} else if (task === '=') {
task=e.target.value;
} else if (lastKeyIsANumber) {
if (e.target.value==='DEL') {
numDisplay.value = numDisplay.value.slice(0,numDisplay.value.length-1);
lastKeyIsANumber = true;
} else if (firstOperation) {
firstOperation = false;
numberOne = numDisplay.value;
task = e.target.value;
clearDisplay = true;
} else {
numberTwo = numDisplay.value;
clearDisplay = true;
operate(numberOne,numberTwo,task);
task = e.target.value;
}
}
});
}
// Keyboard support
calcOperators = ['+','-','=','/','*','Enter']
document.addEventListener('keydown', function(e) {
if (e.which === 13) {
e.key='=';
}
if (Number(e.key) < 10 && e.which != 32) {
setNumber(e.key);
lastKeyIsANumber = true;
} else if (task === '=') {
task=e.key;
} else if (calcOperators.includes(e.key) && lastKeyIsANumber) {
if (firstOperation) {
firstOperation = false;
numberOne = numDisplay.value;
task = e.key;
clearDisplay = true;
} else {
numberTwo = numDisplay.value;
clearDisplay = true;
operate(numberOne,numberTwo,task);
task = e.key;
}
} else if (e.keyCode === 8 && lastKeyIsANumber) {
if (lastKeyIsANumber) {
numDisplay.value = numDisplay.value.slice(0,numDisplay.value.length-1);
lastKeyIsANumber = true;
}
}
});