What this snippet does
let and const are block-scoped, meaning they cannot be accessed outside of the curly braces where they were defined.
Expected output
ReferenceError: a is not defined
Why practise typing this
Typing variables and declarations 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
- Declaring mutable and immutable variablesVariables and Declarations · beginner
- Defining API endpoints and retry countsVariables and Declarations · beginner
- Mutating an object property declared with constVariables and Declarations · beginner
- Inferring a number type from assignmentVariables and Declarations · beginner
- Inferring object propertiesVariables and Declarations · beginner
- Inferring a union type from conditional arraysVariables and Declarations · beginner