Benchmark: 'value === undefined' VS 'typeof value === "undefined"' when value is defined

Script Preparation code:

var value = undefined;

Tests:

value === undefined
value === undefined
typeof value === "undefined"
typeof value === "undefined"

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
value === undefined
typeof value === "undefined"

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):

LLMs can make mistakes. Check important info.

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

**Benchmark Definition:**

The benchmark definition compares two approaches to check if a variable `value` is `undefined`. The two approaches are:

1. `value === undefined`
2. `typeof value === "undefined"`

These two approaches are often used interchangeably, but they have some subtle differences.

**Approach 1: `value === undefined`**

This approach uses the triple equals operator (`===`) to compare the value of `value` with `undefined`. This method is considered more concise and easier to read. However, it has a potential performance overhead due to the language's parsing mechanism.

**Pros:** More concise, easier to read.
**Cons:** Potential performance overhead due to parsing.

**Approach 2: `typeof value === "undefined"`**

This approach uses the `typeof` operator to check the type of `value`. If `value` is `undefined`, then `typeof value` will return `"undefined"`. This method can be slightly faster than the first approach, as it avoids the parsing overhead.

**Pros:** Potential performance improvement due to avoidance of parsing.
**Cons:** More verbose, less concise.

**Library and special features:**

There are no libraries or special features mentioned in the provided JSON. The benchmark only uses built-in JavaScript operators (`===`, `typeof`).

**Other alternatives:**

If you wanted to compare these two approaches in a different way, here are some alternative methods:

* Using `==` instead of `===` for comparison
* Using `value === null` or `value === undefined` (instead of `typeof value === "undefined"`)
* Using a library like Lodash's `isEqual` function to compare the two expressions
* Using a transpiler like Babel to compile the JavaScript code and then comparing the results

However, these alternatives are not part of the original benchmark definition.

**Benchmark preparation code:**

The script preparation code is:
```javascript
var value = undefined;
```
This sets the `value` variable to `undefined`, which is used as the input for both test cases. The HTML preparation code is empty (`null`), indicating that no additional setup is required for the benchmark.

**Test cases:**

There are two individual test cases:

1. "value === undefined"
2. "typeof value === \"undefined\""

Each test case measures the execution time of its respective approach using the `ExecutionsPerSecond` metric.

The latest benchmark result shows the performance comparison between the two approaches on a Chrome 126 browser running on a Mac OS X 10.15.7 system. The results suggest that Approach 2 (`typeof value === "undefined"`) is slightly faster than Approach 1 (`value === undefined`).

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
value === undefined	10799074.0 Ops/sec
typeof value === "undefined"	28515884.0 Ops/sec

Related benchmarks:

'value === undefined' VS 'typeof value === "undefined"' when value is defined (version: 0)

Comparing performance of: value === undefined vs typeof value === "undefined"

Created: 4 years ago by: Guest

Jump to the latest result

value === undefined

typeof value === "undefined"

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 28 days ago):