Benchmark: Object assign vs direct assignment by iterating keys and assigning

Tests:

With Object.assign()
var toSave = { "def":100101102, "ghi":null, "jkl":106107108, "mno":109110111.106107108, "pqr":'112113114', "stu":NaN, "vwx":118119120, "yz{":[ { "vwx":118119120 }, { "vwx":118119120 } ], }; var dest = { "abc":979899 }; if (toSave) { Object.assign(dest, toSave); }
With Iteration and Assignment
var toSave = { "def":100101102, "ghi":null, "jkl":106107108, "mno":109110111.106107108, "pqr":'112113114', "stu":NaN, "vwx":118119120, "yz{":[ { "vwx":118119120 }, { "vwx":118119120 } ], }; var dest = { "abc":979899 }; if (toSave) { var keys = Object.keys(dest); for (var i = 0; i < keys.length; i++) { dest[keys[i]] = toSave[keys[i]]; } }
With Iteration and .keys().forEach
var toSave = { "def":100101102, "ghi":null, "jkl":106107108, "mno":109110111.106107108, "pqr":'112113114', "stu":NaN, "vwx":118119120, "yz{":[ { "vwx":118119120 }, { "vwx":118119120 } ], }; var dest = { "abc":979899 }; if (toSave) { var keys = Object.keys(dest).forEach(key => { dest[key] = toSave[key]; }); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
With Object.assign()
With Iteration and Assignment
With Iteration and .keys().forEach

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36 Edg/135.0.0.0

Browser/OS: Chrome 135 on Windows

View result in a separate tab

Test name	Executions per second
With Object.assign()	12746640.0 Ops/sec
With Iteration and Assignment	94440928.0 Ops/sec
With Iteration and .keys().forEach	96689456.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark compares three approaches to copy an object from `toSave` to `dest`. The two main options are:

1. **Object.assign(dest, toSave)**: This method uses the spread operator (`...`) to create a shallow copy of `toSave` and assigns it to `dest`.
2. **Iteration and assignment**: This approach involves getting the keys of `dest` using `Object.keys(dest)`, iterating over them, and assigning values from `toSave` to corresponding keys in `dest`.

**Pros and Cons**

1. **Object.assign()**
	* Pros:
		+ Fast and efficient, as it uses a built-in method optimized for performance.
		+ Handles nested objects recursively without issues.
	* Cons:
		+ Requires modern JavaScript versions (ECMAScript 2015+) to use the spread operator (`...`).
		+ May not work correctly with certain types of data structures or libraries that modify objects on the fly.
2. **Iteration and assignment**
	* Pros:
		+ Works in older JavaScript versions, as it only relies on built-in `Object.keys()` method.
		+ Can be more readable for developers familiar with manual key-value pairs.
	* Cons:
		+ Slower than `Object.assign()`, especially for large objects.
		+ More error-prone due to the need to manually iterate over keys and handle edge cases.

**Library Usage**

None of the benchmark options rely on external libraries. However, some minor optimizations might be influenced by JavaScript engine-specific features or internal implementation details.

**Special JS Features/Syntax**

The benchmark does not explicitly test any special JavaScript features or syntax beyond what's already described in the options.

**Other Alternatives**

If you're looking for alternative approaches to copy objects, consider:

1. **Shallow copying using `JSON.parse(JSON.stringify())`**: This method creates a new object with cloned properties from the original object.
2. **Using a library like Lodash**: Lodash provides a `cloneDeep()` function that recursively clones complex data structures, including objects.

Keep in mind that each approach has its trade-offs and might be more suitable for specific use cases or performance requirements. The benchmark results should provide insight into which approach is faster and more efficient for the tested scenario.

Related benchmarks:

Object assign vs direct assignment by iterating keys and assigning (version: 0)

Should you be saving your fields to an object with Object.keys(toSave).forEach(k => ... or by Object.assign(destination, toSave);

Comparing performance of: With Object.assign() vs With Iteration and Assignment vs With Iteration and .keys().forEach

Created: 5 years ago by: Registered User

Jump to the latest result

With Object.assign()

With Iteration and Assignment

With Iteration and .keys().forEach

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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