Simplify and document code
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index.html
217
index.html
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@ -64,7 +64,7 @@
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<a href="https://git.fwdekker.com/FWDekker/simplify-fractions/src/branch/master/LICENSE">MIT License</a>.
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Source code available on <a href="https://git.fwdekker.com/FWDekker/simplify-fractions/">git</a>.
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<div style="float: right;">v1.0.11</div>
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<div style="float: right;">v1.0.12</div>
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</section>
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</footer>
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</main>
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@ -75,22 +75,35 @@
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integrity="sha256-nvJJv9wWKEm88qvoQl9ekL2J+k/RWIsaSScxxlsrv8k=" crossorigin="anonymous"></script>
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<script src="https://static.fwdekker.com/js/common.js" crossorigin="anonymous"></script>
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<script>
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/**
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* A fraction that can be simplified.
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*/
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class Fraction {
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constructor(numerator, denominator) {
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if (!isInt(numerator) || !isInt(denominator))
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throw new Error("Numerator and denominator must be integer-like.");
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this.sign = xor(numerator < 0, denominator < 0) ? -1 : 1;
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this.sign = numerator < 0 !== denominator < 0 ? -1 : 1;
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this.numerator = Math.abs(+numerator);
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this.denominator = Math.abs(+denominator);
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}
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/**
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* Returns a new fraction such that the gcd of the numerator and denominator is 1.
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*
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* @returns {Fraction} a new fraction such that the gcd of the numerator and denominator is 1
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*/
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simplify() {
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const common = gcd(this.numerator, this.denominator);
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return new Fraction(this.sign * this.numerator / common, this.denominator / common);
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}
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/**
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* Returns the MathJax string representation of this fraction.
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*
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* @returns {string} the MathJax string representation of this fraction
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*/
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toString() {
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let frac = `\\frac{${this.numerator}}{${this.denominator}}`;
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if (this.sign === -1)
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@ -99,6 +112,12 @@
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return frac;
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}
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/**
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* Returns the MathJax string representation of this fraction, or of the numerator if the denominator is 1.
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*
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* @returns {string} the MathJax string representation of this fraction, or of the numerator if the denominator
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* is 1.
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*/
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toReducedString() {
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if (this.numerator === 0)
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return "0";
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@ -116,125 +135,111 @@
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}
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}
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const xor = (a, b) => (a || b) && !(a && b);
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// noinspection EqualityComparisonWithCoercionJS
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/**
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* Returns `true` if and only if `n` is an integer.
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*
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* @param n {*} the value to check for integerness
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* @returns {boolean} `true` if and only if `n` is an integer
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*/
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const isInt = n => n == parseInt(n);
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const factorize = n => {
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if (!isInt(n))
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return undefined;
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n = +n;
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if (n <= 0)
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return undefined;
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if (n === 1)
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return [1];
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const factors = [];
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while (n % 2 === 0) {
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factors.push(2);
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n /= 2;
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}
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while (n % 3 === 0) {
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factors.push(3);
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n /= 3;
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}
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for (let i = 5; i <= n; i += ((i - 1) % 6 === 0) ? 4 : 2) {
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while (n % i === 0) {
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factors.push(i);
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n /= i;
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}
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}
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return factors;
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};
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const defactorize = factors => {
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let accumulator = 1;
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for (let i = 0; i < factors.length; i++)
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accumulator *= factors[i];
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return accumulator;
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};
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/**
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* Returns the greatest common divisor of `a` and `b`.
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*
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* @param a {number} the first operand
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* @param b {number} the second operand
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* @returns {number} the greatest common divisor of `a` and `b`
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*/
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const gcd = (a, b) => {
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const aFactors = factorize(a);
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const bFactors = factorize(b);
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if (b > a) {
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const temp = a;
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a = b;
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b = temp;
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}
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const overlap = [];
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while (true) {
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if (b === 0) return a;
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a %= b;
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for (let aIndex = 0; aIndex < aFactors.length; aIndex++) {
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const bIndex = bFactors.indexOf(aFactors[aIndex]);
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if (bIndex >= 0) {
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overlap.push(aFactors[aIndex]);
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bFactors.splice(bIndex, 1);
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if (a === 0) return b;
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b %= a;
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}
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};
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doAfterLoad(() => {
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const numeratorInput = $("#numerator");
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const denominatorInput = $("#denominator");
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const submitButton = $("#submit");
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const outputField = $("#out");
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/**
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* Returns `undefined` if the inputs are valid, or a tuple consisting of the invalid element and an explanation
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* of its invalidity otherwise.
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*
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* @returns {(HTMLElement|string)[]|undefined} `undefined` if the inputs are valid, or a tuple consisting of the
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* invalid element and an explanation of its invalidity otherwise
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*/
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const validateInputs = () => {
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let numerator = numeratorInput.value;
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let denominator = denominatorInput.value;
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if (numerator === "")
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return [numeratorInput, "Numerator must not be empty."];
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if (denominator === "")
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return [denominatorInput, "Denominator must not be empty."];
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if (!isInt(numerator))
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return [numeratorInput, "Numerator must be an integer."];
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if (!isInt(denominator))
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return [denominatorInput, "Denominator must be an integer."];
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if (+denominator === 0)
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return [denominatorInput, "Denominator must not be 0."];
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return undefined;
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};
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/**
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* Reads the inputs and tries to output the simplified fraction.
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*
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* Errors are handled and displayed where appropriate.
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*/
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const outputSimplifiedFraction = () => {
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const validationInfo = validateInputs();
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if (validationInfo !== undefined) {
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validationInfo[0].select();
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outputField.innerText = validationInfo[1];
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return;
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}
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}
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return defactorize(overlap);
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};
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const fraction = new Fraction(numeratorInput.value, denominatorInput.value);
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outputField.innerText = "$$" + fraction.toString() + " = " + fraction.simplify().toReducedString() + "$$";
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MathJax.Hub.Queue(["Typeset", MathJax.Hub]);
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};
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const numeratorInput = $("#numerator");
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const denominatorInput = $("#denominator");
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const submitButton = $("#submit");
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const outputField = $("#out");
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submitButton.onclick = () => outputSimplifiedFraction();
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const validateInputs = () => {
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let numerator = numeratorInput.value;
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let denominator = denominatorInput.value;
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numeratorInput.addEventListener("keydown", event => {
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if (event.key === "Enter") {
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if (denominatorInput.value === "") {
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denominatorInput.select();
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} else {
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outputSimplifiedFraction();
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numeratorInput.select();
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}
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}
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});
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if (numerator === "")
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return [numeratorInput, "Numerator must not be empty."];
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if (denominator === "")
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return [denominatorInput, "Denominator must not be empty."];
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if (!isInt(numerator))
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return [numeratorInput, "Numerator must be an integer."];
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if (!isInt(denominator))
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return [denominatorInput, "Denominator must be an integer."];
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if (+denominator === 0)
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return [denominatorInput, "Denominator must not be 0."];
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return undefined;
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};
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const outputSimplifiedFraction = () => {
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const validationInfo = validateInputs();
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if (validationInfo !== undefined) {
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validationInfo[0].select();
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outputField.innerText = validationInfo[1];
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return;
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}
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const fraction = new Fraction(numeratorInput.value, denominatorInput.value);
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outputField.innerText = "$$" + fraction.toString() + " = " + fraction.simplify().toReducedString() + "$$";
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MathJax.Hub.Queue(["Typeset", MathJax.Hub]);
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};
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submitButton.onclick = () => outputSimplifiedFraction();
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numeratorInput.addEventListener("keydown", event => {
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if (event.key === "Enter") {
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if (denominatorInput.value === "") {
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denominatorInput.select();
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} else {
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denominatorInput.addEventListener("keydown", event => {
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if (event.key === "Enter") {
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outputSimplifiedFraction();
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numeratorInput.select();
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denominatorInput.select();
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}
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}
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});
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denominatorInput.addEventListener("keydown", event => {
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if (event.key === "Enter") {
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outputSimplifiedFraction();
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denominatorInput.select();
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}
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});
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});
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</script>
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</body>
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