Simplify and document code

index.html

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