How to enable strict null checks in TypeScript

Strict null checks in TypeScript help catch common programming errors related to null and undefined values by enabling stricter null and undefined checks during compilation. To enable strict null checks in TypeScript, you can follow these steps:

1. tsconfig.json: Open your tsconfig.json file (or create one if it doesn't exist) in the root of your TypeScript project. This file contains configuration options for the TypeScript compiler.

2. Compiler Options: Add or modify the "strict" option to include "strictNullChecks". You can also enable other strict options along with it if you want a more comprehensive set of checks.

   Here's an example tsconfig.json file:

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   {
     "compilerOptions": {
       "target": "es5",
       "module": "commonjs",
       "strict": true,
       "strictNullChecks": true
     }
   }
   

   The "strict": true enables a group of strict options, and "strictNullChecks": true specifically enables strict null checks.

3. Save and Rebuild: Save your tsconfig.json file, and rebuild your TypeScript project. Depending on your setup, you can use the tsc command in the terminal or any build tool that you are using.

Enabling strict null checks will make TypeScript more stringent in checking for null and undefined values, which can help prevent many common programming errors related to nullability.

Keep in mind that enabling strict null checks might require you to update your code to handle nullable values appropriately, such as using optional chaining (?.) or the nullish coalescing operator (??) where needed. This stricter checking is beneficial for catching potential bugs early in the development process.