/
script.js
165 lines (135 loc) · 4.26 KB
/
script.js
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/* DOM selectors */
const calcDisplay = document.querySelector(".calc-display");
const numButtons = document.querySelectorAll(".button-num");
const dotButton = document.querySelector(".button-dot");
const opButtons = document.querySelectorAll(".button-op");
const evalButton = document.querySelector(".button-eval");
const posnegButton = document.querySelector(".button-posneg");
const clearButton = document.querySelector(".button-clear");
const delButton = document.querySelector(".button-del");
/* display text & functions */
let currentDisplayVal = "";
let previousDisplayVal = "";
const updateDisplayText = text => (calcDisplay.textContent = text);
/* calculator functions & variables */
const add = (a, b) => a + b;
const sub = (a, b) => a - b;
const mul = (a, b) => a * b;
const div = (a, b) => a / b;
const operate = (operator, a, b) => {
if (operator === "+") return add(a, b);
if (operator === "-") return sub(a, b);
if (operator === "×") return mul(a, b);
if (operator === "÷") return div(a, b);
};
let currentOperator;
let currentResult;
let resultFlag = false;
/* state functions */
checkDisplayValsExist = () => {
return currentDisplayVal != "" && previousDisplayVal != "";
};
disableEvalButton = () => {
evalButton.style.pointerEvents = "none";
resultFlag = true;
};
enableEvalButton = () => {
evalButton.style.pointerEvents = "auto";
};
checkResultPossible = () => {
return (
currentDisplayVal != "" && previousDisplayVal != "" && currentOperator != ""
);
};
disableButtons = () => {
document.querySelectorAll(".calc-button").forEach(button => {
button.style.pointerEvents = "none";
});
clearButton.style.pointerEvents = "auto";
};
enableButtons = () => {
document.querySelectorAll(".calc-button").forEach(button => {
button.style.pointerEvents = "auto";
});
};
function evaluateValues() {
if (currentOperator === "÷" && currentDisplayVal == 0) {
updateDisplayText("This kills the calculator");
return;
}
currentDisplayVal = String(
operate(
currentOperator,
Number(previousDisplayVal),
Number(currentDisplayVal)
)
);
updateDisplayText(currentDisplayVal);
}
/* event functions */
function numButtonPress(event) {
if (resultFlag) {
//if the result button is previously hit, clear values to start
resultFlag = false;
currentDisplayVal = "";
currentOperator = "";
}
currentDisplayVal += event.target.textContent.trim();
updateDisplayText(currentDisplayVal);
if (checkDisplayValsExist()) {
enableEvalButton();
}
}
function opButtonPress(event) {
if (resultFlag) {
//if the result button is previously hit, reset the values so the op button doesnt evaluate
resultFlag = false;
previousDisplayVal = "";
currentOperator = "";
}
if (checkResultPossible()) {
evaluateValues();
}
currentOperator = event.target.textContent.trim();
if (currentDisplayVal != "") previousDisplayVal = currentDisplayVal;
currentDisplayVal = "";
}
function evalButtonPress(event) {
evaluateValues();
disableEvalButton();
}
// figure out bug here when pressed after opkey
function posnegButtonPress(event) {
currentDisplayVal *= -1;
currentDisplayVal = currentDisplayVal.toString(); // retype to string
updateDisplayText(currentDisplayVal);
}
function clearButtonPress(event) {
disableEvalButton();
currentDisplayVal = "";
previousDisplayVal = "";
currentOperator = "";
previousOperator = "";
updateDisplayText(currentDisplayVal);
}
function delButtonPress(event) {
currentDisplayVal = currentDisplayVal.slice(0, -1);
updateDisplayText(currentDisplayVal);
}
function dotButtonPress(event) {
if (currentDisplayVal.includes(".")) {
currentDisplayVal = currentDisplayVal.replace(".", "");
}
currentDisplayVal += ".";
updateDisplayText(currentDisplayVal);
}
/* event listeners */
numButtons.forEach(button => button.addEventListener("click", numButtonPress));
opButtons.forEach(button => button.addEventListener("click", opButtonPress));
dotButton.addEventListener("click", dotButtonPress);
evalButton.addEventListener("click", evalButtonPress);
posnegButton.addEventListener("click", posnegButtonPress);
clearButton.addEventListener("click", clearButtonPress);
delButton.addEventListener("click", delButtonPress);
/* initialize states */
disableEvalButton();