Step 3 / Select topic TypeScript Types Medium

What this bank covers

• infer in an array pattern
• Multiple infer sites in covariant positions
• infer with tuple rest patterns
• Recursive conditional type with infer
• Return-type inference and the false branch
• infer inside a template literal type
• Adding `?` in a mapped type
• Homomorphic mapped types copy `readonly`
• Filtering keys by mapping them to `never`
• Mapping over tuples and arrays
• Transforming the value type in a mapped type
• Renaming keys without changing value types
• Adding the `readonly` modifier
• `keyof` of a key-filtered mapped type
• Removing modifiers with `-readonly`
• Key remapping plus the `-?` modifier
• Template literals distribute over unions
• Capitalize inside a template literal type
• Matching a `${string}` placeholder
• infer in a template literal pattern
• Key remapping with a template literal
• Cross product of two union placeholders
• Two infer placeholders split at the first separator
• Template literal types constrain exact string shapes
• Capitalize inside a template literal union
• Recursive inference with template literal patterns
• Naked type parameter distributes
• Tuple wrapping blocks distribution
• never is the empty union
• Filtering a union by distribution
• infer inside a distributive conditional
• Distributed object union as an annotation
• never with a non-distributive conditional
• Both branches can appear
• Non-distributive check picks one branch
• true | false collapses to boolean
• Array covariance
• Downcasting an array
• Return type covariance
• Method parameter bivariance
• Property covariance
• Readonly collections and assignability
• Array to tuple assignability
• Inference picks a common supertype
• Parameter arity in assignability
• Supertype values in subtype positions
• Overload resolution return type
• satisfies keeps the inferred type
• satisfies and excess properties
• satisfies is not a cast
• First matching overload wins
• Union arguments and overloads
• Implementation must cover every overload
• satisfies supplies a contextual type
• as const combined with satisfies
• Arity in overload resolution
• Distributing a conditional type over a discriminated union
• Indexed access on a boolean discriminant
• Excluding every member of a discriminated union
• Selecting one member with Extract, then indexing it
• Only shared properties are readable before narrowing
• Object literals checked against a discriminated union
• Exhaustiveness checking with never
• Narrowing a union with the in operator
• Comparing a discriminant to a value outside the union
• Narrowing removes the other members' properties
• Indexed access through a tuple constraint
• Structural constraint on a shape
• keyof constraint with indexed access return
• Constraint versus default type argument
• Literal inference under a primitive constraint
• The object constraint and strict null checks
• Inferred return type from an indexed access
• Readonly array as an upper bound
• Returning a type parameter through its constraint
• infer inside a constrained conditional type
• Recursive conditional flattening
• Recursive dotted-path indexed access
• Recursive tuple accumulation
• Recursive JSON union
• Self-referencing object type
• Indexed access through an index signature
• Indexed access with a union key
• Recursive template literal join
• Recursive readonly mapped type
• Illegal direct self-reference
• Template literal inference is shortest-match
• Multiple inference sites for one infer variable
• Blocking distribution to detect never
• Conditional types applied to any
• Assigning to a filtered union type
• Inferring the last tuple element
• infer with an extends constraint
• Multiple infer candidates in covariant positions
• infer candidates in contravariant positions
• Where `infer` is allowed
• Branch order in a nested conditional type
• Comparing two deferred conditional types