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TypeScriptAsync, Promises & Error Handling Types

78 items

1

Typing for-await-of Loop Variables

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2

Typing .then() and .catch() Handlers

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Why Promise Rejections Aren't Typed

Slides / Video
4

Void-Returning Promises and Fire-and-Forget

Slides / Video
5

Typing Promise Executor Callbacks

Slides / Video
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Result Union Types for Success and Failure

Slides / Video
7

Custom Error Classes and Typing Them

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8

The useUnknownInCatchVariables Flag

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Narrowing unknown Errors in catch

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Catch Clause Errors Are unknown

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11

Typing race, allSettled, and any

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Typing Promise.all Tuple Results

Slides / Video
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Typing await and Unwrapped Values

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14

The Promise<T> Type Parameter

Slides / Video
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Async Function Return Types

Slides / Video
16

Chained then Return Value

Code Quiz
17

Narrowing an unknown Error

Code Quiz
18

Typing the Executor Callback

Code Quiz
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instanceof Error Narrowing

Code Quiz
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catch Variable Is unknown

Code Quiz
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Typing catch Handler Parameter

Code Quiz
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Custom Error Class Typing

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Reading allSettled Results

Code Quiz
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Wrong Resolved Value Type in Promise

Code Quiz
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Floating Promise Not Awaited

Code Quiz
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Discriminated Result Type

Code Quiz
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Typing an async Generator

Code Quiz
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Iterating an AsyncIterable

Code Quiz
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async Function Returning void

Code Quiz
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Always-Throwing Function Return Type

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Promise Type Has One Parameter

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Typing an async Arrow Function

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Typing Promise.resolve and reject

Code Quiz
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Awaiting a Non-Promise Value

Code Quiz
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Promise.all Result Tuple Types

Code Quiz
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await Outside an async Function

Code Quiz
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Awaiting Unwraps the Value Type

Code Quiz
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Async Function Return Type

Code Quiz
39

Typing a Promise with Promise<T>

Code Quiz
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Promise.race Return Type

Code Quiz
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Typing Promise.all Result Tuples

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Floating Promise Concerns

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void vs Promise<void> in Async Contexts

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Typing Callback-to-Promise Wrappers

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for await...of Element Typing

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Async Generators and AsyncIterable Types

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Typing then/catch Callback Chains

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Result / Either Pattern for Typed Errors

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never Return Type for Throwing Functions

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Typing Rejected Promise Values

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Custom Error Class Typing

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instanceof Error Narrowing in catch

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Narrowing Errors in catch Blocks

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useUnknownInCatchVariables Flag

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catch Clause Variable Typing

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Promise Executor and resolve/reject Typing

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Typing Promise.allSettled Result Shape

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Typing Promise.race and Promise.any

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Typing async Function Return Values

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Promise<T> Type Annotation

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await Expression Result Types

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Errors Are Typed as unknown in catch

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The Promise<T> Type

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Explicitly Annotating async Return Types

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useUnknownInCatchVariables Flag

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66

Narrowing Caught Errors with instanceof

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67

Void vs Undefined Return in Async Callbacks

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68

Typing Promise Resolution Values

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Typing Promise.all Results as a Tuple

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70

Typing Promise.race and Promise.allSettled

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71

Custom Error Class Typing

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72

Typing the Promise Executor Callbacks

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73

The never Type in Throwing Functions

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Result/Either Pattern for Error Handling

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Chaining Promises and Return Type Flow

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76

PromiseSettledResult Types

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77

Awaiting a Promise and the Resulting Type

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78

async Function Return Type Inference

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Slides / VideoIntermediate

Why Promise Rejections Aren't Typed

Promise<T> only describes the resolved value — the rejection reason is always untyped because anything can be thrown.

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