Maximize TypeScript strictness

Enable all options for enforcing type safety.  Fix uncovered violations.

Author: wimpyprogrammer

demo/src/demo.ts

@@ -41,7 +41,7 @@ function generatePattern(words: string): RegExp {
 	return pattern;
 }
 
-let clearSuccessIndicatorHandle: number;
+let clearSuccessIndicatorHandle: NodeJS.Timeout;
 function displayPattern(pattern: RegExp): void {
 	$output.value = pattern.toString();
 	$output.dispatchEvent(new Event('input'));

demo/src/utils/wordList.spec.ts

@@ -14,7 +14,7 @@ describe('parseString', () => {
 			expect(wordList).toEqual([]);
 		}
 
-		['', null, undefined].forEach(testInput);
+		['', null, undefined].forEach(val => testInput(val as string));
 	});
 
 	it('returns entire input string in array when delimiter is empty', () => {
@@ -23,7 +23,7 @@ describe('parseString', () => {
 			expect(wordList).toEqual([' some input string ']);
 		}
 
-		['', null, undefined].forEach(testDelimiter);
+		['', null, undefined].forEach(val => testDelimiter(val as string));
 	});
 
 	it('returns entire input string in array when delimiter is not present in input string', () => {

demo/webpack.config.js

@@ -13,7 +13,10 @@ module.exports = {
 					{
 						loader: 'ts-loader',
 						options: {
-							compilerOptions: { noEmit: false },
+							compilerOptions: {
+								checkJs: false, // workaround for TypeStrong/ts-loader#702
+								noEmit: false,
+							},
 							configFile: resolve(__dirname, './tsconfig.json'),
 						},
 					},

package.json

@@ -43,6 +43,7 @@
     "@types/escape-string-regexp": "^1.0.0",
     "@types/jest": "^24.0.18",
     "@types/jest-when": "^2.7.0",
+    "@types/node": "^12.7.5",
     "@typescript-eslint/eslint-plugin": "^2.2.0",
     "@typescript-eslint/parser": "^2.2.0",
     "eslint": "6.1.0",

tsconfig.json

@@ -2,8 +2,10 @@
 	"compilerOptions": {
 		"allowJs": true,
 		"baseUrl": "./",
+		"checkJs": true,
 		"downlevelIteration": true,
 		"esModuleInterop": true,
+		"forceConsistentCasingInFileNames": true,
 		"rootDir": "./",
 		"lib": [
 			"es5",
@@ -14,12 +16,13 @@
 		],
 		"module": "es2015",
 		"noEmit": true,
-		"noImplicitAny": true,
+		"noImplicitReturns": true,
 		"noUnusedLocals": true,
 		"noUnusedParameters": true,
 		"pretty": true,
 		"skipLibCheck": true,
-		"sourceMap": true
+		"sourceMap": true,
+		"strict": true
 	},
 	"include": ["src"]
 }

yarn.lock

@@ -939,6 +939,11 @@
   resolved "https://registry.yarnpkg.com/@types/json5/-/json5-0.0.29.tgz#ee28707ae94e11d2b827bcbe5270bcea7f3e71ee"
   integrity sha1-7ihweulOEdK4J7y+UnC86n8+ce4=
 
+"@types/node@^12.7.5":
+  version "12.7.5"
+  resolved "https://registry.yarnpkg.com/@types/node/-/node-12.7.5.tgz#e19436e7f8e9b4601005d73673b6dc4784ffcc2f"
+  integrity sha512-9fq4jZVhPNW8r+UYKnxF1e2HkDWOWKM5bC2/7c9wPV835I0aOrVbS/Hw/pWPk2uKrNXQqg9Z959Kz+IYDd5p3w==
+
 "@types/stack-utils@^1.0.1":
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/@types/stack-utils/-/stack-utils-1.0.1.tgz#0a851d3bd96498fa25c33ab7278ed3bd65f06c3e"