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lodash forEach vs for i loop with length cached
(version: 0)
Comparing performance of:
lodash.forEach vs native
Created:
6 years ago
by:
Guest
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HTML Preparation code:
<script src="https://cdn.jsdelivr.net/lodash/4.16.0/lodash.min.js"></script>
Script Preparation code:
var values = [{a: 30310}, {b: 100303}, {c: 3040494}]
Tests:
lodash.forEach
var count = 0; _.forEach(values, function(v,i) { if (v.a != null) { count++; } })
native
var count = 0; for (var i = 0, len = values.length; i < len; i++) { if (values[i].a != null) { count++; } }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
lodash.forEach
native
Fastest:
N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks. **Benchmark Context** MeasureThat.net is a website where users can create and run JavaScript microbenchmarks to compare the performance of different approaches. In this case, we're comparing the performance of two methods: using Lodash's `forEach` function versus a traditional `for...i loop` with length caching. **Test Case 1: Lodash.forEach** The first test case measures the performance of Lodash's `forEach` function. The benchmark definition code is: ```javascript _.forEach(values, function(v,i) { if (v.a != null) { count++; } }); ``` This code uses the `forEach` function to iterate over the `values` array and increments a counter whenever an object in the array has a property named `a`. **Test Case 2: Native for...i loop with length caching** The second test case measures the performance of a traditional `for...i loop` with length caching. The benchmark definition code is: ```javascript var count = 0; for (var i = 0, len = values.length; i < len; i++) { if (values[i].a != null) { count++; } } ``` This code uses a `for` loop to iterate over the `values` array and increments a counter whenever an object in the array has a property named `a`. The length of the array is cached in the `len` variable to avoid repeated lookups. **Performance Comparison** The performance comparison between these two approaches depends on various factors, such as: * **Cache locality**: The Lodash `forEach` function uses an internal array buffer to store the iteration state, which can lead to better cache locality compared to the traditional `for...i loop`. * **Loop overhead**: The traditional `for...i loop` has more overhead due to the need to increment the loop counter and check the length of the array on each iteration. * **Array indexing**: In modern JavaScript engines, array indexing is often optimized using SIMD instructions, which can lead to faster performance for iterative algorithms like this one. **Pros and Cons** * Lodash `forEach`: + Pros: Cache-friendly, optimized for array iteration. + Cons: Requires an additional library dependency (Lodash), may have slower startup times due to lazy initialization. * Traditional `for...i loop` with length caching: + Pros: No external dependencies, can be faster in some cases due to reduced overhead. + Cons: Less cache-friendly, requires manual array indexing and loop counter management. **Library: Lodash** Lodash is a popular JavaScript utility library that provides a wide range of functional programming tools and helpers. In this case, the `forEach` function is used as a simple iteration tool to iterate over arrays and objects. **Special JS Feature or Syntax** None mentioned in this benchmark. **Other Alternatives** If you need more control over array iteration or want to avoid using Lodash, other alternatives include: * **Array.prototype.forEach()**: This is the built-in `forEach` method on the Array prototype, which provides similar functionality to Lodash's implementation. * **ES6 for...of loop**: This is a newer syntax for iterating over arrays and objects that can provide better performance and readability in some cases. * **Custom iteration functions**: You can also implement your own custom iteration function using a loop or recursion, depending on the specific requirements of your use case.
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