Benchmark: obj vs array again

Script Preparation code:

list = Array.from({
    length: 1000
}, (v, i) => ({
    id: 'id' + i
}));
obj = list.reduce((acc, cur) => {
    acc[cur.id] = cur;
    return acc;
}, {});

Tests:

update in array
const list2 = list.map(item => item.id === 'id500' ? {...item, updated: true} : item)
update in obj
const obj2 = {...obj, id500: {...obj['id500'], updated: true}}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
update in array
update in obj

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's dive into the provided benchmark code.

**What is being tested?**

The provided JSON represents a JavaScript microbenchmark that compares two approaches:

1. Updating an element directly in an array (`obj vs array again`).
2. Updating a single object property using the dot notation (i.e., `obj['id500']`) versus using the bracket notation with an object literal (i.e., `obj.id500 = { ... }`).

**Options being compared:**

Two approaches are compared:

1. **Updating directly in the array (`list.map()`)**:
	* This approach updates each element of the array by modifying its properties.
	* The resulting updated array is stored in a new variable (`const list2 = ...`).
2. **Updating using the dot notation (`obj['id500']`) or bracket notation with an object literal (`obj.id500 = { ... }`)**:
	* These approaches update only the specific property of the `obj` object identified by its key.
	* The second approach uses a new object literal to create and assign a new value to the target property.

**Pros and cons:**

1. **Updating directly in the array (`list.map()`)**:
	* Pros:
		+ Simple and concise syntax.
		+ No need to create a temporary object or perform explicit assignment.
	* Cons:
		+ Modifies the original array, which might be unexpected behavior.
		+ May lead to unnecessary re-assignments if not properly optimized.
2. **Updating using the dot notation (`obj['id500']`) or bracket notation with an object literal (`obj.id500 = { ... }`)**:
	* Pros:
		+ Only updates the specific property without modifying the original object.
		+ Can be more readable and maintainable when working with complex objects.
	* Cons:
		+ Requires explicit assignment using `=` or a new object literal, which might add overhead.

**Library usage:**

The provided benchmark code uses no external libraries. It relies solely on standard JavaScript features and syntax.

**Special JS feature or syntax:**

There are no special JS features or syntax used in this benchmark. However, it does utilize some advanced ES6 features like:

* Arrow functions (`(v, i) => ({...})`)
* Object literals (`{ ... }`)
* Template literals (`\r\n`)

If you're not familiar with these features, don't worry – they are widely supported and commonly used in modern JavaScript development.

**Alternative approaches:**

For similar benchmarking or optimization purposes, you might want to explore other approaches:

1. **Using `forEach()` instead of `map()`:**
	* This approach would update each element in the array by modifying its properties using a callback function.
2. **Using `Object.assign()` for updating objects:**
	* This approach would create a new object with updated properties and assign it back to the original object.

When working on microbenchmarks like this, consider the trade-offs between simplicity, readability, and performance when choosing your approach.

Related benchmarks:

obj vs array again (version: 0)

Comparing performance of: update in array vs update in obj

Created: 5 years ago by: Guest

Jump to the latest result

update in array

update in obj

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):