feat(degree): better degree to angle handling

src/degree.js

@@ -0,0 +1,103 @@
+// @ts-nocheck
+const ANGLE = Symbol('angle-rad');
+const DEG_TO_RAD = Math.PI / 180;
+const RAD_TO_DEG = 180 / Math.PI;
+
+/**
+ * @typedef {Degree & number} DegreeType
+ * @typedef {IDegree & number} IDegreeType
+ * @abstract
+ */
+class ADegree {
+  /**
+   *
+   * @param {number | ADegree} angle
+   */
+  constructor(angle) {
+    if (angle instanceof ADegree) {
+      this[ANGLE] = angle[ANGLE];
+    } else {
+      this[ANGLE] = normRad(angle * DEG_TO_RAD);
+    }
+  }
+
+  /**
+   * @returns {number}
+   */
+  valueOf() {
+    return this[ANGLE];
+  }
+
+  /**
+   * @returns {string}
+   */
+  toString() {
+    return `${this[ANGLE] * RAD_TO_DEG}deg`;
+  }
+}
+
+export class Degree extends ADegree {
+  /**
+   *
+   * @param {number | Degree | IDegree} angle
+   */
+  set(angle) {
+    if (angle instanceof ADegree) {
+      this[ANGLE] = angle[ANGLE];
+    } else {
+      this[ANGLE] = degToRad(angle);
+    }
+  }
+}
+
+export class IDegree extends ADegree {
+  /**
+     * @returns {Degree}
+     */
+  toDegree() {
+    return new Degree(this[ANGLE]);
+  }
+}
+
+/**
+ * @typedef {(angle: number) => DegreeType} DegreeNum
+ * @typedef {(angle: Degree | IDegree) => DegreeType} DegreeDeg
+ * @typedef {DegreeNum & DegreeDeg}
+ *
+ * @param {number | Degree | IDegree} angle
+ * @returns {DegreeType}
+ * @hidden
+ */
+export function degree(angle) {
+  return new Degree(angle);
+}
+
+/**
+ * @typedef {(angle: number) => IDegreeType} IDegreeNum
+ * @typedef {(angle: Degree | IDegree) => IDegreeType} IDegreeDeg
+ * @typedef {IDegreeNum & IDegreeDeg}
+ *
+ * @param {number | Degree | IDegree} angle
+ * @returns {IDegreeType}
+ * @hidden
+ */
+export function idegree(angle) {
+  if (angle instanceof IDegree) {
+    return angle;
+  }
+  return new IDegree(angle);
+}
+
+export const Export = {
+  /**
+   * @param {number | Degree | IDegree} angle
+   * @returns {IDegreeType}
+   */
+  idegree: angle => idegree(angle),
+
+  /**
+   * @param {number | Degree | IDegree} angle
+   * @returns {DegreeType}
+   */
+  degree: angle => degree(angle),
+};

src/formatter.js

@@ -27,7 +27,7 @@ function normalizeNumber(number) {
   return { mant, exp };
 }
 
-export default function formatNumber(nr, digits) {
+export function formatNumber(nr, digits) {
   const n = normalizeNumber(nr);
   n.mant /= 10;
   n.exp += 1;