Скачать или смотреть How to Efficiently Sort and Filter an Array of Hashes with Underscore.js

Discover how to use `underscore.js` to efficiently find the highest price for each tokenId in an array of hashes. Learn to optimize your code with minimal iterations!
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How to Efficiently Sort and Filter an Array of Hashes with Underscore.js

Working with collections of data can often be a tricky task, particularly when you want to perform operations such as sorting and filtering while maintaining efficiency. A common scenario developers face is needing to filter out specific data based on certain criteria. In this blog, we'll tackle a specific problem: How do you extract the highest price for each tokenId in an array of hashes using underscore.js?

The Problem

Given the following JavaScript array of objects, where each object has a tokenId and a price, we need to generate a new array that contains only the objects with the highest price for each tokenId. Here's the sample data we will work with:

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

The final result we aim for should be:

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

The Solution

Using reduce for Efficiency

Instead of iterating through the array multiple times, we can achieve our goal in a single iteration by utilizing the reduce function provided by underscore.js. Here's how it works step-by-step:

Initialization: Create an accumulator object that will hold the maximum price values indexed by tokenId.

Iteration: For each entry in the data array, check if the tokenId already exists in our accumulator. If it does, compare the current price with the stored price and keep the higher one.

Return Value: Finally, convert the accumulator back into the desired format by constructing an array from its entries.

Implementation Code

Here is the complete code implementing the above logic using reduce:

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

Breakdown of the Code

Accumulate Maximum Prices: The key line in the reduce function checks whether the current tokenId is already present in the accumulator and updates it if the current price is higher.

Efficiency: The entire operation is completed in a single pass through the data, making it much more efficient than nested loops.

Conclusion

Using the reduce method from underscore.js, we have efficiently filtered the array to obtain the highest price per tokenId in just a single iteration. This not only simplifies the code but also enhances performance significantly, especially when dealing with larger datasets.

By applying these techniques, you can streamline your data handling processes in JavaScript and deliver more efficient solutions. Happy coding!