Benchmark: globals vs. upvalues: immutable

HTML Preparation code:

<script>
'use strict';

const l = (function() {
  'use strict';
  const localObj = `foobar`;
  return function() {
    return localObj[3];
  };
})();

Function(`return this`)().globalObj = `foobAr`;

const g = function() {
  'use strict';
  return globalObj[3];
};

Object.defineProperty(
	Function(`return this`)(),
	`globalObj2`,
	{value : `fooBar`, __proto__ : null,});

const g2 = function() {
  'use strict';
  return globalObj2[3];
};
  
const s1 = function() {
  'use strict';
  return Symbol.for('foobar');
};

var rv = ``;
var rv2;

</script>

Tests:

g
rv = g();
g2
rv = g2();
l
rv = l();
s1
rv2 = s1();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
g
g2
l
s1

Fastest: N/A

Slowest: N/A

Latest run results:

No previous 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 break down the provided benchmark and explain what's being tested.

**Overview**

The benchmark compares the performance of three different approaches to access properties of objects in JavaScript:

1. **Immutable global variables**: Using immutable global variables to store data.
2. **Upvalues**: Using upvalues, a mechanism introduced in ECMAScript 2015 (ES6) that allows functions to "remember" their context and capture variables from the surrounding scope.

**Options being compared**

The benchmark compares the performance of accessing properties using:

1. **Immutable global variables**: The `globalObj` variable is declared as a global constant, making it immutable.
2. **Upvalues**: The `g` function uses upvalues to access the `globalObj` variable, which is defined earlier in the script.

**Pros and cons**

**Immutable global variables:**

Pros:

* Easy to understand and implement
* No memory management concerns

Cons:

* Can lead to performance issues due to object lookup (e.g., accessing properties like `globalObj[3]`)
* Global scope can lead to naming conflicts

**Upvalues:**

Pros:

* Efficient access to captured variables without modifying the original context
* Memory-efficient, as upvalues only store a reference to the captured variable

Cons:

* Can be challenging to understand and implement for developers unfamiliar with ES6 syntax
* May introduce additional complexity when debugging or optimizing code

**Other considerations**

The benchmark also uses `Symbol.for()` to create a symbol that can be used as an identifier. This feature was introduced in ECMAScript 2015 (ES6) and provides a way to uniquely identify values.

**Library and purpose**

No external library is required for this benchmark. The script itself implements the necessary functionality.

**Special JS features or syntax**

The benchmark uses ES6-specific features, such as:

* `const` and `let` declarations
* Function expressions (e.g., `function() { ... }`)
* Upvalues (introduced in ECMAScript 2015)
* `Symbol.for()` to create a symbol

**Alternatives**

To write similar benchmarks, you could consider the following alternatives:

1. Use an existing benchmarking framework like Benchmark.js or Microbenchmark.
2. Create a custom benchmark script using your preferred programming language and testing framework (e.g., Jest or Mocha).
3. Modify the provided benchmark script to focus on specific aspects of performance comparison.

Keep in mind that the choice of alternative will depend on your specific needs, expertise, and preferences.

Related benchmarks:

globals vs. upvalues: immutable (version: 1)

Comparing performance of: g vs g2 vs l vs s1

Created: 8 years ago by: Registered User

Jump to the latest result

g

g2

l

s1

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):