Benchmark: Testing for false vs === undefined vs hasOwnProperty vs in for undefined member

Tests:

test truth
var n = {}; while(true) { if(!n.foo) break; }
test undefined
var n = {}; while(true) { if(n.foo===undefined) break; }
test hasOwnProperty
var n = {}; while(true) { if(!n.hasOwnProperty('foo')) break; }
test in ===
var n = {}; while(true) { if('foo' in n === false) break; }
test in !
var n = {}; while(true) { if(!('foo' in n)) break; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
test truth
test undefined
test hasOwnProperty
test in ===
test in !

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/108.0.0.0 Safari/537.36

Browser/OS: Chrome 108 on Windows

View result in a separate tab

Test name	Executions per second
test truth	1078204800.0 Ops/sec
test undefined	12296229.0 Ops/sec
test hasOwnProperty	160367280.0 Ops/sec
test in ===	1127436672.0 Ops/sec
test in !	1126103936.0 Ops/sec

Autogenerated LLM Summary (model llama3.1:latest, generated 2 months ago):

LLMs can make mistakes. Check important info.

Let's dive into the benchmarking test case.

**What is being tested?**

The test case is evaluating the performance of different ways to check if an object has a specific property in JavaScript.

**Test cases:**

There are five test cases:

1. `test truth`: Checking if `n.foo` exists without using any special syntax or libraries.
2. `test undefined`: Using the triple equals (`===`) operator to check if `n.foo` is strictly equal to `undefined`.
3. `test hasOwnProperty`: Using the `hasOwnProperty()` method on the object `n` to check if it has a property named `'foo'`.
4. `test in ===`: Using the `in` operator with a truthy value (`=== false`) to check if `'foo'` is a property of the object `n`.
5. `test in !`: Similar to the previous test, but using a falsy value (`!`) instead of a truthy one.

**Libraries and special features:**

None are used in this test case.

**Options being compared:**

The test cases compare the performance of different ways to check if an object has a specific property:

1. `n.foo` ( simple existence check)
2. `n.foo === undefined` (checking for strict equality with `undefined`)
3. `n.hasOwnProperty('foo')` (using the `hasOwnProperty()` method)
4. `'foo' in n === false` and `!('foo' in n)` (using the `in` operator with a truthy or falsy value)

**Pros and cons:**

* `n.foo`: Simple and easy to read, but may be slower than other methods.
* `n.foo === undefined`: Strictly checks for equality with `undefined`, but may not work correctly in some edge cases (e.g., when the property exists but has a value of `undefined`).
* `n.hasOwnProperty('foo')`: Returns `true` if the property exists, regardless of its value. This is a good choice if you need to check for existence without considering the value.
* `'foo' in n === false` and `!('foo' in n)`: These methods use the `in` operator with a truthy or falsy value to check for existence. They are generally faster than using `hasOwnProperty()` but may be less readable.

**Other considerations:**

* When working with objects, it's essential to consider whether you need to check for strict equality (`===`) or just existence (using the `in` operator).
* If performance is critical, using the `in` operator with a truthy value might be a good choice.
* The test case results suggest that the `test in !` approach is the fastest on Chrome 108.

**Alternatives:**

Other ways to check for object property existence include:

1. Using the `hasOwnProperty()` method (as shown in this test case).
2. Using the `in` operator with a truthy value (e.g., `'foo' in n === false` or `!('foo' in n)`).
3. Checking if the property is present in an object literal using the syntax `obj.prop === undefined`.
4. Utilizing libraries like Lodash, which provides a more comprehensive set of utility functions for working with objects.

Feel free to ask follow-up questions if you need further clarification!

Related benchmarks:

Testing for false vs === undefined vs hasOwnProperty vs in for undefined member (version: 0)

Is there a performance benefit to replacing === undefined with a logical test?

Comparing performance of: test truth vs test undefined vs test hasOwnProperty vs test in === vs test in !

Created: one year ago by: Guest

Jump to the latest result

test truth

test undefined

test hasOwnProperty

test in ===

test in !

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.1:latest, generated 2 months ago):