Refactor code to comply with ESLint rules

Major refactoring using ESLint with rules from AirBnb and Vue.

Enable most of the ESLint rules and do necessary linting in the code.
Also add more information for rules that are disabled to describe what
they are and why they are disabled.

Allow logging (`console.log`) in test files, and in development mode
(e.g. when working with `npm run serve`), but disable it when
environment is production (as pre-configured by Vue). Also add flag
(`--mode production`) in `lint:eslint` command so production linting is
executed earlier in lifecycle.

Disable rules that requires a separate work. Such as ESLint rules that
are broken in TypeScript: no-useless-constructor (eslint/eslint#14118)
and no-shadow (eslint/eslint#13014).

src/application/Parser/CategoryParser.ts

@@ -1,71 +1,86 @@
-import { CategoryData, ScriptData, CategoryOrScriptData } from 'js-yaml-loader!@/*';
+import {
+  CategoryData, ScriptData, CategoryOrScriptData, InstructionHolder,
+} from 'js-yaml-loader!@/*';
 import { Script } from '@/domain/Script';
 import { Category } from '@/domain/Category';
 import { parseDocUrls } from './DocumentationParser';
 import { ICategoryCollectionParseContext } from './Script/ICategoryCollectionParseContext';
 import { parseScript } from './Script/ScriptParser';
 
-let categoryIdCounter: number = 0;
+let categoryIdCounter = 0;
 
 interface ICategoryChildren {
-    subCategories: Category[];
-    subScripts: Script[];
+  subCategories: Category[];
+  subScripts: Script[];
 }
 
-export function parseCategory(category: CategoryData, context: ICategoryCollectionParseContext): Category {
-    if (!context) { throw new Error('undefined context'); }
-    ensureValid(category);
-    const children: ICategoryChildren = {
-        subCategories: new Array<Category>(),
-        subScripts: new Array<Script>(),
-    };
-    for (const data of category.children) {
-        parseCategoryChild(data, children, category, context);
-    }
-    return new Category(
-        /*id*/ categoryIdCounter++,
-        /*name*/ category.category,
-        /*docs*/ parseDocUrls(category),
-        /*categories*/ children.subCategories,
-        /*scripts*/ children.subScripts,
-    );
+export function parseCategory(
+  category: CategoryData,
+  context: ICategoryCollectionParseContext,
+): Category {
+  if (!context) { throw new Error('undefined context'); }
+  ensureValid(category);
+  const children: ICategoryChildren = {
+    subCategories: new Array<Category>(),
+    subScripts: new Array<Script>(),
+  };
+  for (const data of category.children) {
+    parseCategoryChild(data, children, category, context);
+  }
+  return new Category(
+    /* id: */ categoryIdCounter++,
+    /* name: */ category.category,
+    /* docs: */ parseDocUrls(category),
+    /* categories: */ children.subCategories,
+    /* scripts: */ children.subScripts,
+  );
 }
 
 function ensureValid(category: CategoryData) {
-    if (!category) {
-        throw Error('category is null or undefined');
-    }
-    if (!category.children || category.children.length === 0) {
-        throw Error(`category has no children: "${category.category}"`);
-    }
-    if (!category.category || category.category.length === 0) {
-        throw Error('category has no name');
-    }
+  if (!category) {
+    throw Error('category is null or undefined');
+  }
+  if (!category.children || category.children.length === 0) {
+    throw Error(`category has no children: "${category.category}"`);
+  }
+  if (!category.category || category.category.length === 0) {
+    throw Error('category has no name');
+  }
 }
 
 function parseCategoryChild(
-    data: CategoryOrScriptData,
-    children: ICategoryChildren,
-    parent: CategoryData,
-    context: ICategoryCollectionParseContext) {
-    if (isCategory(data)) {
-        const subCategory = parseCategory(data as CategoryData, context);
-        children.subCategories.push(subCategory);
-    } else if (isScript(data)) {
-        const scriptData = data as ScriptData;
-        const script = parseScript(scriptData, context);
-        children.subScripts.push(script);
-    } else {
-        throw new Error(`Child element is neither a category or a script.
+  data: CategoryOrScriptData,
+  children: ICategoryChildren,
+  parent: CategoryData,
+  context: ICategoryCollectionParseContext,
+) {
+  if (isCategory(data)) {
+    const subCategory = parseCategory(data as CategoryData, context);
+    children.subCategories.push(subCategory);
+  } else if (isScript(data)) {
+    const scriptData = data as ScriptData;
+    const script = parseScript(scriptData, context);
+    children.subScripts.push(script);
+  } else {
+    throw new Error(`Child element is neither a category or a script.
                 Parent: ${parent.category}, element: ${JSON.stringify(data)}`);
-    }
+  }
 }
 
-function isScript(data: any): boolean {
-    return (data.code && data.code.length > 0)
-        || data.call;
+function isScript(data: CategoryOrScriptData): data is ScriptData {
+  const holder = (data as InstructionHolder);
+  return hasCode(holder) || hasCall(holder);
 }
 
-function isCategory(data: any): boolean {
-    return data.category && data.category.length > 0;
+function isCategory(data: CategoryOrScriptData): data is CategoryData {
+  const { category } = data as CategoryData;
+  return category && category.length > 0;
+}
+
+function hasCode(holder: InstructionHolder): boolean {
+  return holder.code && holder.code.length > 0;
+}
+
+function hasCall(holder: InstructionHolder) {
+  return holder.call !== undefined;
 }