Benchmark: delete vs null vs undefined vs void 0 vs Object.create(null)3

Tests:

null
var a = undefined for(var i = 0; i < 1000;i++) { if (a === null) { } }
undefined
var a = undefined; for(var i = 0; i < 1000;i++) { if (a === undefined) {}; }
Object.create(null)
var a = undefined; for(var i = 0; i < 1000;i++) { if (a === void 0) {}; }
void 0
var a = 999; for(var i = 0; i < 1000;i++) { a = void 0; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
null
undefined
Object.create(null)
void 0

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.

I'll break down the provided benchmark and explain what's being tested, the options compared, their pros and cons, and other considerations.

**Benchmark Definition**

The `delete vs null vs undefined vs void 0 vs Object.create(null)` benchmark tests different ways of checking for a non-existent variable in JavaScript. The variable is initially set to:

*   `undefined`
*   `null`
*   `void 0` (equivalent to `null`)
*   A new object created with `Object.create(null)`
*   `999` (a number, not a variable)

The benchmark runs a loop of 1000 iterations and checks the condition in each iteration. If the condition is true, it does nothing.

**Options Compared**

1.  **delete**: The `delete` operator removes a property from an object. However, this only works if the property exists in the object.
    *   Pros: Efficient, as it directly interacts with the object's internal data structure.
    *   Cons: Not applicable to variables that don't exist in memory.
2.  **null**: Checking `null` is a common method for determining an uninitialized variable.
    *   Pros: Widely supported and easy to implement.
    *   Cons: Can lead to performance issues if used excessively, as it involves a comparison operation.
3.  **undefined**: Similar to `null`, but also supports primitive values like numbers, strings, etc., which might not be initialized or set explicitly.
    *   Pros: Supports various data types and is generally considered safer than `null`.
    *   Cons: May still lead to performance issues if used in large loops.
4.  **void 0**: A shorthand for checking if a variable is null or undefined.
    *   Pros: Compact and easy to read, but similar performance concerns as `undefined`.
5.  **Object.create(null)**: Creates an object with no prototype chain, simulating an uninitialized variable.
    *   Pros: Directly checks the existence of the object in memory.
    *   Cons: Requires more code than traditional methods.

**Library and Special JS Features**

There are no libraries or special JavaScript features being used in this benchmark.

**Device Platform, Browser, and OS**

The test results show data from a single device platform (Desktop), browser (Chrome 97), and operating system (Windows).

**Considerations**

*   The use of `delete` may not be applicable to modern JavaScript environments that don't support it as a primitive operator.
*   Some versions of Internet Explorer still support the `delete` operator but with different behavior, which might affect compatibility.

**Alternatives**

Other alternatives for checking variables could include:

1.  Using a boolean flag or variable to track initialization status
2.  Implementing custom checks using bitwise operations or property existence tests (e.g., `in`)
3.  Utilizing language-specific features like TypeScript's null safety mechanisms

Keep in mind that these alternatives might not be as straightforward or widely supported as the options compared in this benchmark.

Related benchmarks:

delete vs null vs undefined vs void 0 vs Object.create(null)3 (version: 0)

delete vs null vs undefined vs void 0 vs Object.create(null)

Comparing performance of: null vs undefined vs Object.create(null) vs void 0

Created: 7 years ago by: Guest

Jump to the latest result

null

undefined

Object.create(null)

void 0

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):