Add legacy preset

Author: voxpelli

README.md

@@ -29,6 +29,7 @@ Then in your `tsconfig.json`, it [`extends`](https://www.typescriptlang.org/tsco
 ### Generic ones
 
 * `base` – where most of the configuration is set
+* `legacy` – like `base` but for older TypeScript versions – version 4.5 and onward
 * `recommended` – like `base` but adds a [`target`](https://www.typescriptlang.org/tsconfig#target) set to `ES2015`
 
 ### Node specific ones

legacy.json

@@ -0,0 +1,40 @@
+{
+  "$schema": "https://json.schemastore.org/tsconfig",
+  "display": "Legacy",
+
+  "compilerOptions": {
+    "module": "commonjs",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": false,
+    "removeComments": true,
+
+    /* My own additions */
+
+    /* Make it a JS-targeted config */
+    "allowJs": true,
+    "checkJs": true,
+    "noEmit": true,
+    "resolveJsonModule": true,
+
+    /* New checks being tried out */
+    "exactOptionalPropertyTypes": true,
+    "noImplicitOverride": true,
+    "noPropertyAccessFromIndexSignature": true,
+    "noUncheckedIndexedAccess": true,
+
+    /* Additional checks */
+    "forceConsistentCasingInFileNames": true,
+    // Skipped as implicit "return undefined" at end of function is okay + explicit clashes with ESLint "no-useless-return"
+    // "noImplicitReturns": false,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true
+
+    /* To make strict checking somewhat less strict during a transition stage, add one or more of: */
+    /*
+    "noImplicitThis": false,
+    "noImplicitAny": false,
+    "strictNullChecks": false,
+    */
+  }
+}