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Asynchronous Programming in NestJS

Asynchronous Programming in NestJS

Get a brief introduction to asynchronous programming in NestJS.

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In programming, synchronous and asynchronous operations define how tasks are executed. Synchronous tasks run one after another in a predictable sequence. Asynchronous tasks allow tasks to run independently and concurrently. They don’t block the execution flow, enabling the program to continue working on other tasks while waiting for the completion of async tasks. Asynchronous code is essential for handling tasks with potentially long execution times, such as network requests or database queries.

Async and await

NestJS has good support for async functions. To define an asynchronous function in NestJS, we can use the async and await keywords. Below is a contrived example:

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 @Get()
 async getAll(): Promise<any> {
   // Perform some asynchronous operation here
   const data = await this.someAsyncOperation();
   return data;
 }

In line 2, the async keyword denotes the getAll function as asynchronous. This designation allows us to use the await keyword within that function. The await keyword is used in asynchronous functions to pause the function’s execution until an asynchronous operation is completed. The async and await keywords are often used together to make it easier to work with asynchronous functions.

It’s essential to pair the await keyword with async in order to enable asynchronous execution. If we add the async keyword to a synchronous method (a synchronous method means that ...