math/math.html at master · RichCaloggero/math · GitHub

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<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Math</title>
</head>
<body>
<h1>Math</h1>
<div id="message" role="status" style="position:absolute; left: -9999; top: -9999;"></div>
<div id="error" role="status"></div>

<div id="container">
<div id="results" role="log"></div>

<div id="input">
<label>Expression: <input autofocus type="text" id="expression" accesskey="e"></label>
<label>announce only result when browsing history: <input type="checkbox" id="result-only" accesskey="r"></label>
</div>
</div>


<script src="math.min.js"></script>

<script>
const container = document.querySelector("#container");
const results = document.querySelector("#results");
const expression = document.querySelector("#expression");
const error = document.querySelector("#error");
const message = document.querySelector("#message");
const resultOnly = document.querySelector("#result-only");
let resultCount = 0;
let history = null;

const parser = math.parser();
parser.set("clear", function () {parser.clear(); return "All symbols removed.";});

resultOnly.addEventListener("change", e => setAnnouncement(e.target.checked));

expression.addEventListener("click", e => {
const expression = e.target.value.trim();
if (expression === "") return;
execute(expression);
e.target.value = "";
});

results.addEventListener("click", e => {
const container = e.target.matches(".result-container")? e.target : e.target.parentElement ;
const _expression = container.querySelector(".input-expression").textContent;
expression.value = _expression;
expression.focus();
});

expression.addEventListener("keydown", e => {
if (e.key === "Enter" && !e.shiftKey && !e.altKey && !e.ctrlKey) {
e.preventDefault();
e.target.click();
return;
} // if

if (e.key === "ArrowUp" || e.key === "ArrowDown") {
history = getHistory(history, e.key === "ArrowUp"? -1 : 1);
e.preventDefault();
return;
} // if

if (e.ctrlKey && (e.key === "Home" || e.key === "End")) {
if (e.key === "Home") history = getHistory(results.children[0]);
else history = getHistory(null);

e.preventDefault();
return;
} // if
}); // keydown


function execute (expression) {
try {
displayResult(expression, parser.evaluate(expression));
history = null;
} catch (e) {
displayError(e);
} // try
} // execute

function displayResult (expression, result) {
parser.evaluate(`$_ = "${result}"`);
results.appendChild(createResult(expression, result, resultCount++));
} // displayResult

function displayError (e) {
error.textContent = e.message;
console.error (e);
} // displayError

function createResult(expression, result, count) {
const id = `result-${count}`;
const container = document.createElement("div");
container.className = "result-container";
container.id = id;
container.innerHTML = `
<div class="input-expression">${expression}</div>
<div class="result-expression">${result}</div>
`;

if (resultOnly.checked) {
container.querySelector(".result-expression").tabIndex = 0;
message.textContent = container.querySelector(".result-expression").textContent;
} else {
container.tabIndex = 0;
} // if

return container;
} // createResult

function setAnnouncement (resultOnly) {
results.querySelectorAll("[tabindex]").forEach(x => x.removeAttribute("tabindex"));

results.querySelectorAll(
resultOnly? ".result-expression" : ".result-container"
).forEach(x => x.tabIndex = 0);

resultOnly? results.removeAttribute("role") : results.setAttribute("role", "log");
} // setAnnouncement

function getHistory (history, direction = 0) {
if (direction !== 0) {
if (direction === 1 && !history) return null;

const _history = history;
history = direction === -1? historyPrevious(history) : historyNext(history);
if (direction === -1 && !history) return _history;
} // if

expression.value = history?
history.querySelector(".input-expression").textContent : "";

return history;
} // getHistory

function historyPrevious (history) {
if (history) {
history = history.previousElementSibling;
} else {
history = results.children[results.children.length-1];
} // if

return history;
} // historyPrevious

function historyNext (history) {
if (history) {
history = history.nextElementSibling;
} else {
history = results.children[0];
} // if

return history;
} // historyNext


</script>
</body>
</html>