TypeScript.

Static type system for JavaScript at any scale. Covers 13 sub-skills.

• TypeScript · 1 of 3

  Types & Inference

  Which annotation describes an array of numbers?

  A{number}Bnumber[]Cnumber()D[number]

• TypeScript · 2 of 3

  Template Literal Types

  Given type T = "on" | "off", which type expression yields the union "onClick" | "offClick" using template literal types?

  A${T}ClickB$[T]ClickC#{T}ClickD{T}Click

• TypeScript · 3 of 3

  Template Literal Types

  Why might TypeScript produce a combinatorial explosion with template literal types?

  AThe TypeScript compiler cannot cache template literal type resultsBUnion types in interpolation positions multiply out exponentiallyCTemplate literal types bypass the normal union size limit of 100DTemplate literal types evaluate eagerly, consuming excessive memory