Refactor

src/framework/helper/create-element.ts

@@ -1,6 +1,7 @@
 import { html } from '../../model/misc';
 
 export const createElement = (from: html): HTMLElement => {
+  // won't work for all elements, eg.: <td>
   const element: HTMLElement = document.createElement('div');
   element.innerHTML = from;
   return element.firstElementChild as HTMLElement;

src/framework/helper/get-height.ts

@@ -1,7 +1,7 @@
 export const getHeight = (e: HTMLElement): number => {
+  // ignores margin collapse
   const computedStyle = window.getComputedStyle(e);
   return (
-    // ignores margin collapse
     e.clientHeight +
     parseInt(computedStyle.marginTop) +
     parseInt(computedStyle.marginBottom) +

src/framework/helper/last.ts

@@ -1,2 +1,2 @@
 export const last = <T>(list: Array<T>): T =>
-  list.length > 0 ? list[list.length - 1] : undefined;
+  list.length >= 1 ? list[list.length - 1] : undefined;

src/framework/helper/mix-colors.ts

@@ -1,25 +1,25 @@
-export const mixColors = (
-  hexColorA: string,
-  hexColorB: string,
-  quantityA: number
-): string => {
-  const colorA = hexToRGB(normalizeHex(hexColorA));
-  const colorB = hexToRGB(normalizeHex(hexColorB));
+export type hex = string;
+export type rgb = [number, number, number];
 
-  const mixedColor: [number, number, number] = [
+export const mixColors = (
+  hexColorA: hex,
+  hexColorB: hex,
+  quantityA: number
+): hex => {
+  const colorA = hexToRGB(hexColorA);
+  const colorB = hexToRGB(hexColorB);
+
+  const mixedColor: rgb = [
     mix(colorA[0], colorB[0], quantityA),
     mix(colorA[1], colorB[1], quantityA),
     mix(colorA[2], colorB[2], quantityA),
   ];
 
-  return RGBToHex(mixedColor);
+  return rgbToHex(mixedColor);
 };
 
-const hexToRGB = ([r1, r2, g1, g2, b1, b2]: string): [
-  number,
-  number,
-  number
-] => {
+const hexToRGB = (hex: hex): rgb => {
+  const [r1, r2, g1, g2, b1, b2] = normalizeHex(hex);
   return [
     Number.parseInt(r1 + r2, 16),
     Number.parseInt(g1 + g2, 16),
@@ -27,7 +27,7 @@ const hexToRGB = ([r1, r2, g1, g2, b1, b2]: string): [
   ];
 };
 
-const normalizeHex = (hex: string): string => {
+const normalizeHex = (hex: hex): hex => {
   hex = hex.trim();
   if (hex.startsWith('#')) {
     hex = hex.substr(1);
@@ -37,5 +37,5 @@ const normalizeHex = (hex: string): string => {
 
 const mix = (a: number, b: number, q: number): number => a * q + b * (1 - q);
 
-const RGBToHex = (rgb: [number, number, number]): string =>
+const rgbToHex = (rgb: rgb): hex =>
   '#' + rgb.map(n => Math.round(n).toString(16)).join('');

src/framework/helper/random.ts

@@ -2,16 +2,17 @@ export class Random {
   public constructor(private seed: number) {}
 
   public get next(): number {
+    // result is in [0, 1)
     return (
       ((2 ** 31 - 1) & (this.seed = Math.imul(48271, this.seed))) / 2 ** 31
     );
   }
 
   public choose<T>(list: Array<T>): T {
-    return list[this.randomInInterval(0, list.length)];
+    return list[Math.floor(this.randomInInterval(0, list.length))];
   }
 
   public randomInInterval(aClosed: number, bOpen: number): number {
-    return Math.floor((bOpen - aClosed) * this.next) + aClosed;
+    return (bOpen - aClosed) * this.next + aClosed;
   }
 }

src/framework/helper/range.ts

@@ -1,15 +0,0 @@
-export const range = ({
-  from = 0,
-  to = Infinity,
-  step = 1,
-}: {
-  from?: number;
-  to?: number;
-  step?: number;
-}): Iterable<number> => {
-  return {
-    *[Symbol.iterator]() {
-      for (let i = from; i < to; yield i, i += step) {}
-    },
-  };
-};