/
calculator.js
119 lines (100 loc) · 2.56 KB
/
calculator.js
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let buffer = "0";
let runningTotal = 0;
let previousOperator;
const screen = document.querySelector(".screen");
function buttonClick(value) {
if (isNaN(parseInt(value))) {
// if the value is not a number --> which means it is a symbol!!
handleSymbols(value);
}
else {
handleNumbers(value);
}
// we will call the rerender function here
// So whenever, anyone clicks on the button, they see current value
rerender();
}
function handleNumbers(number) {
if (buffer === '0') {
buffer = number;
}
else {
buffer += number;
}
}
function handleMathOperations(symbol) {
if (buffer === "0") {
// do nothing !1
return;
}
const intBuffer = parseInt(buffer);
if (runningTotal === 0) {
runningTotal = intBuffer;
}
else {
flushOperations(intBuffer);
}
previousOperator = symbol;
buffer = '0';
}
function flushOperations(value) {
// Perform all the Math Operations !!
if (previousOperator === '+') {
runningTotal += value;
}
else if (previousOperator === '/') {
runningTotal /= value;
}
else if (previousOperator === 'x') {
runningTotal *= value;
}
else if (previousOperator === '-') {
runningTotal -= value;
}
// console.log(runningTotal);
}
function handleSymbols(symbol) {
// console.log(symbol + " Symbol!!");
switch (symbol) {
case 'C':
buffer = '0';
break;
case '⬅':
if (buffer.length === 1) {
buffer = "0";
}
else {
buffer = buffer.substring(0, buffer.length - 1);
}
break;
case '=':
if (previousOperator === null) {
// need two numbers to do Math
return;
}
flushOperations(parseInt(buffer));
previousOperator = null;
buffer = "" + runningTotal;
runningTotal = 0;
break;
case '+':
case '/':
case 'x':
case '-':
// console.log("Math Operations!!");
handleMathOperations(symbol);
break;
}
}
function initialize() {
console.log("INITIALIZED !!");
document.querySelector(".grid-container")
.addEventListener("click", function (event) {
buttonClick(event.target.innerText);
})
}
// rerender function updates the value on the Screen of the Calculator !!
function rerender() {
screen.innerText = buffer;
}
initialize();