What this snippet does
Without the flag, .call accepts any arguments; with it, TypeScript catches the string-to-number mismatch.
Expected output
Compile Error: Argument of type 'string' is not assignable to parameter of type 'number'.
Why practise typing this
Typing strict compiler flags 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
- Failing to initialize a class propertyStrict Compiler Flags · intermediate
- Initializing properties via the constructorStrict Compiler Flags · intermediate
- Using the definite assignment assertion operatorStrict Compiler Flags · intermediate
- Type-safe usage of callStrict Compiler Flags · intermediate
- Binding a method with correct context and argumentsStrict Compiler Flags · intermediate
- Declaring an unused variableStrict Compiler Flags · intermediate