What this snippet does
strictNullChecks separates null and undefined from other types, preventing a large class of runtime null reference errors.
Expected output
Compile Error: Type 'null' is not assignable to type 'string'.
Why practise typing this
Typing tsconfig & compiler code builds muscle memory for the symbols and indentation TypeScript uses most, which prose-based typing tests never cover. DevType measures your words per minute and accuracy on this snippet and tracks the individual characters you mistype, so later lessons can target them.
More TypeScript practice
- Enabling strict mode in tsconfigtsconfig & Compiler · intermediate
- Strict null checks preventing undefined accesstsconfig & Compiler · intermediate
- Implicit any in function parameters under stricttsconfig & Compiler · intermediate
- Checking for null before accessing propertiestsconfig & Compiler · intermediate
- Array index access returns T instead of T | undefinedtsconfig & Compiler · intermediate
- Catching implicit any in variablestsconfig & Compiler · intermediate