How to Work with BigDecimal in Scala.js for Your JavaScript Applications

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The Challenge

Imagine you've created a simple Scala object that exports a method returning a BigDecimal. Here’s a quick look at that Scala object:

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You then call this method from your JavaScript application, but you find yourself confused and stuck. Here’s a snippet of JavaScript code that illustrates the problem:

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In the browser console, you notice that the structure of result is quite complex and not directly usable within JavaScript:

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This complex internal structure prevents you from performing straightforward mathematical operations, leading to frustration.

Understanding the Problem

Key Points to Keep in Mind:

JavaScript Numbers: JavaScript primarily uses the number type, which is a double-precision floating-point. It cannot directly handle Scala's BigDecimal as it is not a primitive type.

Solutions to the Problem

1. Use Double Instead (When Possible)

If you don’t need the precision that BigDecimal provides, consider simply returning a Double type instead of BigDecimal. This reduces complexity, as JavaScript handles Double natively as a number. Your Scala code would look like this:

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

2. Export Additional Methods for BigDecimal Manipulation

If you need to retain BigDecimal for its semantics, you will have to export additional methods that allow JavaScript to interact with BigDecimal. For instance, you might create methods for basic arithmetic:

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

In this way, JavaScript can send BigDecimal instances back and forth while relying on defined methods to perform operations.

3. String Representation of BigDecimal

Another alternative is to convert BigDecimal to a String and return that for use in your JavaScript app. This is particularly useful for displaying results without needing to perform arithmetic operations directly in JavaScript:

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

In your JavaScript code, you can then parse this string back to a number if needed.

Conclusion

Key Takeaway

Always remember that direct manipulation of Scala types in JavaScript may not work as expected. Adjusting your design to accommodate type