TypeScript 2.4

Question 1

dynamic import()

Answer 1

Promise-returning; can be await’ed

Question 2

enum members can contain

Answer 2

string initializers

Question 3

enums can be used in discriminated union types

Answer 3

type Shape = Circle | Square;

Question 4

better inferring types, esp. with . . .

Answer 4

generics

Question 5

TypeScript has always compared parameters in a . . .

Answer 5

bivariant way

Question 6

a “weak type” is an interface with . . .

Answer 6

all optional params

Question 7

what is an index signature

Answer 7

index signature to the weak type (i.e. [propName: string]: any) - can be anything as long as it’s not already defined as a property name

Question 8

even assigning the entire ReadonlyArray back to a ___ is illegal

Answer 8

normal array

Question 9

values that won’t change: ___ use const whereas ___ use readonly

Answer 9

variables / properties

Question 10

values that won’t change: ___ use const whereas ___ use readonly

Answer 10

variables / properties

Question 11

___ get special treatment and undergo ___ when assigning them to other variables, or passing them as arguments

Answer 11

Object literals / excess property checking

Question 12

type assertion

Answer 12

(i.e. opts as Options)

Question 13

function type

Answer 13

interface SearchFunc {
(source: string, subString: string): boolean;
}

Answer 14

This index signature states that when a StringArray is indexed with a number, it will return a string.

Question 15

tagged union type

Answer 15

a union type whose member types all define a discriminant property of a literal type (TS2.0)

Question 16

There are two types of supported index signatures

Answer 16

string and number

Question 17

tagged union type example

Answer 17

interface PayPal {
kind: “paypal”;
email: string;
}

interface CreditCard {
    kind: "credit";
    cardNumber: string;
    securityCode: string;
}

Question 18

class-interface merging

Answer 18

declaring both a class and an interface of the same name