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script.js
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script.js
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let num1 = "";
let num2 = "";
let currentOperator = "";
let chainedOperator = "";
const displayedEquation = document.querySelector("#screen-equation");
const displayedNumber = document.querySelector("#screen-number");
document.querySelectorAll(".number").forEach(button => button.addEventListener('click', () => {
if (button.id === "decimal" && displayedNumber.textContent.includes(".")) return;
// This happens after a calculation is made
if (num1 != "" && currentOperator === "") clear();
if (displayedNumber.textContent === "0" && button.textContent != ".") displayedNumber.textContent = "";
displayedNumber.textContent = removeCommasFromNumber(displayedNumber.textContent);
displayedNumber.textContent += button.textContent;
displayedNumber.textContent = addCommasToNumber(displayedNumber.textContent);
}))
document.querySelectorAll(".operator").forEach(button => button.addEventListener("click", () => {
// This case only happens at the beginning or after pressing AC
if (num1 === "" && num2 === "") {
num1 = parseFloat(removeCommasFromNumber(displayedNumber.textContent));
currentOperator = button.textContent;
displayedEquation.textContent = `${addCommasToNumber(num1)} ${currentOperator}`;
displayedNumber.textContent = "";
} else {
// In this case, num1 is already in memory
// if there's nothing in the screenNumber, that means user wants to change operator
if (displayedNumber.textContent === "") {
currentOperator = button.textContent;
displayedEquation.textContent = `${addCommasToNumber(num1)} ${currentOperator}`;
}
// otherwise, user is done inputting num2 and wants to chain calculation
chainedOperator = button.textContent;
num2 = parseFloat(removeCommasFromNumber(displayedNumber.textContent));
if (isNaN(num2)) {
return;
};
let result = calculate(num1, num2, currentOperator);
if (result === "ERROR") {
showError();
return;
}
displayedEquation.textContent = `${addCommasToNumber(result)} ${chainedOperator}`;
displayedNumber.textContent = "";
num1 = result;
num2 = "";
currentOperator = chainedOperator;
chainedOperator = "";
}
}))
document.querySelector("#equal-operator").addEventListener('click', () => {
if (currentOperator) num2 = parseFloat(removeCommasFromNumber(displayedNumber.textContent));
else return;
if (isNaN(num2)) {
return;
};
let result = calculate(num1, num2, currentOperator);
if (result === "ERROR") {
showError();
return;
}
displayedEquation.textContent = `${addCommasToNumber(num1)} ${currentOperator} ${addCommasToNumber(num2)} =`
displayedNumber.textContent = addCommasToNumber(result);
num1 = result;
num2 = "";
currentOperator = "";
})
document.querySelector("#ac").addEventListener('click', () => {
clear();
})
document.querySelector("#del").addEventListener('click', () => {
// In this case, this is showing a result, not in the process of inputting a number
if (num1 && !currentOperator) return;
if (displayedNumber.textContent === "") return;
displayedNumber.textContent = displayedNumber.textContent.split('').slice(0, -1).join('');
if (displayedNumber.textContent === "") displayedNumber.textContent = "0";
})
function calculate(a, b, operator) {
if (a === "" && b === "" && !operator) return 0
else if (b === "" || !operator) return a;
let result;
switch (operator) {
case "+":
result = a + b;
break;
case "-":
result = a - b;
break;
case "x":
result = a * b;
break;
case "/":
if (b === 0) {
return "ERROR";
}
result = a / b;
break
}
let numDecimal = 10000000;
result = Math.round(result * numDecimal) / numDecimal;
return result;
}
function clear() {
num1 = "";
num2 = "";
currentOperator = "";
chainedOperator = "";
displayedEquation.textContent = "";
displayedNumber.textContent = "0";
document.querySelectorAll("button").forEach(button => {
button.removeAttribute("disabled");
})
}
function showError() {
num1 = "";
num2 = "";
currentOperator = "";
chainedOperator = "";
displayedEquation.textContent = "";
displayedNumber.textContent = "ERROR";
document.querySelectorAll("button").forEach(button => {
if (button.id === "ac") return
else button.setAttribute("disabled", "true");
})
}
function removeCommasFromNumber(number) {
if (typeof(number) != "string") number = number.toString();
return number.replace(/\,/g,'');
}
function addCommasToNumber(number) {
if (typeof(number) != "string") number = number.toString();
const regexPattern = /(\d)(?=(\d{3})+$)/g;
if (number.includes(".")) {
splitNumber = number.split(".");
wholeNumber = splitNumber[0].replace(regexPattern, "$1,");
fractionNumber = splitNumber[1];
return number = `${wholeNumber}.${fractionNumber}`;
} else {
return number.replace(regexPattern, "$1,");
}
}