Mastering async/await in Angular: Ensuring Methods Run in Order

Discover how to properly use `async/await` in Angular 12 to ensure methods execute in a specific sequence. Learn the step-by-step process to manage asynchronous calls effectively.
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Ensuring Method Execution Order Using async/await in Angular

In Angular development, especially when dealing with asynchronous operations such as rendering HTML or manipulating data, managing the order of method execution can be challenging. One common scenario developers encounter is needing to execute two methods sequentially, ensuring that the first method completes before executing the second. This guide explores how to use async/await effectively in Angular to handle such situations.

The Problem

Consider the following scenario: you have two methods, part1 and part2. You want part2 to execute only after part1 has finished its operation. The catch? part1 uses the html2canvas library to generate a canvas from a DOM element, which is inherently asynchronous. If not handled properly, this can lead to your application attempting to execute part2 before part1 has completed, causing unpredicted behavior.

Here’s how these methods look:

[[See Video to Reveal this Text or Code Snippet]]

The Solution

To resolve this issue, we can leverage JavaScript's async/await functionality. This allows us to pause execution of one function until a promise is resolved, effectively ensuring that our two methods run in the correct order. Here’s how to revise our methods:

Step 1: Modify part1 to Return a Promise

First, we need part1 to return a promise that resolves when html2canvas has finished processing. Here's the modified version:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Modify part2 to Also Return a Promise

Although part2 might seem straightforward, wrapping it in a promise can help standardize our code and make error handling easier:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Sequence Execution in the main Method

Lastly, we’ll adjust the main method to utilize async/await to call part1 and wait for its completion before executing part2:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By implementing async/await, you can effectively manage the order of asynchronous method execution in Angular. This not only ensures that your code runs smoothly without unexpected behaviors but also enhances readability and maintainability.

In summary, you learned:

How to modify existing methods to return promises.

How to implement async/await to control the flow of method execution.

With these techniques, you have a solid foundation for managing asynchronous operations in Angular applications. Happy coding!