Benchmark: Property Assignment vs Symbol Assignment with existing properties

Script Preparation code:

window.sym = Symbol("key");
window.obj = {a: 1, b: 2, key: "initial", [sym]: "initial"};

Tests:

Property
obj.key = "value";
Symbol
obj[sym] = "value";

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Property
Symbol

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the provided JSON and explain what is being tested, compared, and the pros and cons of each approach.

**Benchmark Definition**

The first section of the JSON defines a benchmark named "Property Assignment vs Symbol Assignment with existing properties". This benchmark tests how JavaScript handles property assignment using both regular properties (e.g., `obj.key = "value"`) and symbols (e.g., `obj[sym] = "value"`).

**Script Preparation Code**

The script preparation code initializes two variables:

1. `window.sym`: Creates a new symbol named `sym` on the global object (`window`). Symbols are unique values that cannot be reassigned or used as property names.
2. `window.obj`: Creates an object `obj` with three properties: `a`, `b`, and `key`. The `key` property is initialized with the value `"initial"`. Additionally, a symbol `sym` is assigned to the `obj` object as its fourth property.

**Html Preparation Code**

There is no HTML preparation code provided, which means that this benchmark does not involve any DOM-related operations or interactions.

**Individual Test Cases**

The next section defines two individual test cases:

1. **Property**: This test case assigns a value `"value"` to the `key` property of the `obj` object using regular assignment (`obj.key = "value"`).
2. **Symbol**: This test case assigns a value `"value"` to the `sym` property of the `obj` object using symbol notation (`obj[sym] = "value"`).

**Libraries and Special JS Features**

There are no libraries mentioned in this benchmark, but there is an example of a special JavaScript feature: symbols. Symbols were introduced in ECMAScript 2015 (ES6) as a way to create unique property names that cannot be used with other syntax.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **Regular Property Assignment (`obj.key = "value"`)`:
	* Pros: Widely supported across browsers, easy to read and write.
	* Cons: Can lead to collisions if multiple objects share the same property name, reducing performance.
2. **Symbol Notation (`obj[sym] = "value"`)`:
	* Pros: Unique property names reduce conflicts, improve performance by avoiding hash table lookups.
	* Cons: Less readable and more verbose than regular assignment, may not be supported in older browsers.

**Other Alternatives**

In addition to the above approaches, you might consider using other methods for creating unique property names:

1. **Computed Property Names**: You can use a computed value as the property name, which can avoid collisions. For example: `obj["computed-key"] = "value"`.
2. **Merging Objects with Unique Keys**: If performance is critical, you can merge objects using a library like Lodash's `_.assignIn()` method, which can help reduce conflicts.

Keep in mind that these alternatives may have different trade-offs and may not be suitable for all use cases.

I hope this explanation helps!

Related benchmarks:

Property Assignment vs Symbol Assignment with existing properties (version: 0)

Comparing performance of: Property vs Symbol

Created: 5 years ago by: Guest

Jump to the latest result

Property

Symbol

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):