Let's dive into the world of JavaScript microbenchmarks!

What is tested?

On MeasureThat.net, users can create and run JavaScript microbenchmarks to compare different approaches for merging objects. The benchmark tests three popular libraries: Lodash, Deepmerge, and Lodash/FP (Functional Programming).

The individual test cases demonstrate how each library merges two objects, a and b, using the following syntax:

var a = { a: 'oh', b: 'my', c: { a: 'a', b: { c: 'c' } } };
var b = { c: { b: { d: 'a'  }, c: { d: 'd' } } };

The test cases are:

1. Lodash _.merge(): var c = _.merge({}, a, b);
2. Object.assign: var c = object.assign({}, a, b); (not explicitly shown in the benchmark code, but implied)
3. Lodash/FP fp.merge(): var c = fp.merge(b, a);

Options compared

The benchmark compares three different approaches for merging objects:

1. Lodash (_.merge()): Lodash is a utility library that provides a wide range of functions for manipulating data, including object merging. The _merge() function takes multiple arguments and returns a new object with the merged properties.
2. Object.assign: This is a built-in JavaScript method that allows you to copy properties from one or more source objects into a target object.
3. Lodash/FP (fp.merge()): Lodash/FP is a functional programming variant of Lodash, which provides a different set of functions for manipulating data.

Pros and Cons

Here's a brief summary of the pros and cons of each approach:

1. Lodash (_.merge()):
   • Pros: widely supported, flexible, and extensible.
   • Cons: can be slower than other approaches due to its overhead.
2. Object.assign:
   • Pros: built-in JavaScript method, fast, and lightweight.
   • Cons: limited functionality compared to Lodash's _.merge().
3. Lodash/FP (fp.merge()):
   • Pros: functional programming approach, concise code.
   • Cons: may be less familiar or intuitive for developers without prior experience.

Library explanations

1. Deepmerge: Deepmerge is a lightweight library that provides a simple and efficient way to merge objects. It's designed to be fast and flexible, making it suitable for various use cases.
2. Lodash: Lodash is a comprehensive utility library that provides a wide range of functions for manipulating data. Its _.merge() function is an essential part of the library.

Special JS features

The benchmark doesn't explicitly mention any special JavaScript features or syntax. However, it's worth noting that some of these libraries (e.g., Lodash) might require additional setup or configuration, such as importing dependencies using ES modules or commonJS.

Alternatives

Other alternatives for merging objects in JavaScript include:

1. ES6 Object Spread Operator ({ ...a, ...b }): This is a shorthand way to merge two objects using the spread operator.
2. JSON Merge Patch: This library provides a simple and efficient way to merge JSON objects.

In conclusion, MeasureThat.net's benchmark allows users to compare different approaches for merging objects in JavaScript, providing valuable insights into their performance characteristics. By understanding the pros and cons of each approach, developers can make informed decisions about which solution best suits their specific use case.