Benchmark: undefined vs. typeof vs. in vs. hasOwnProperty big object

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5,  e1: 5, e2: 5, e3: 5, e4: 5, e5: 5, e6: 5, e7: 5, e8: 5, e9: 5, e0: 5, ea: 5, eb: 5, ec: 5, ed: 5, ee: 5, ef: 5, eg: 5, eh: 5, ei: 5, ej: 5, ek: 5, el: 5, em: 5, en: 5, eo: 5, ep: 5, eq: 5, er: 5, es: 5, et: 5, eu: 5, ev: 5, ew: 5, ex: 5, ey: 5, ez: 5, f1: 5, f2: 5, f3: 5, f4: 5, f5: 5, f6: 5, f7: 5, f8: 5, f9: 5, f0: 5, fa: 5, fb: 5, fc: 5, fd: 5, fe: 5, ff: 5, fg: 5, fh: 5, fi: 5, fj: 5, fk: 5, fl: 5, fm: 5, fn: 5, fo: 5, fp: 5, fq: 5, fr: 5, fs: 5, ft: 5, fu: 5, fv: 5, fw: 5, fx: 5, fy: 5, fz: 5, g1: 5, g2: 5, g3: 5, g4: 5, g5: 5, g6: 5, g7: 5, g8: 5, g9: 5, g0: 5, ga: 5, gb: 5, gc: 5, gd: 5, ge: 5, gf: 5, gg: 5, gh: 5, gi: 5, gj: 5, gk: 5, gl: 5, gm: 5, gn: 5, go: 5, gp: 5, gq: 5, gr: 5, gs: 5, gt: 5, gu: 5, gv: 5, gw: 5, gx: 5, gy: 5, gz: 5};

Tests:

undefined
undefined !== obj.gr;
typeof
'undefined' !== typeof obj.gr;
in
'gr' in obj;
hasOwnProperty
obj.hasOwnProperty( 'gr' );
bool
!! obj.gr;
keys
Object.keys(obj).includes('gr');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
typeof
in
hasOwnProperty
bool
keys

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 10 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
undefined	119628232.0 Ops/sec
typeof	167676672.0 Ops/sec
in	166039568.0 Ops/sec
hasOwnProperty	47412796.0 Ops/sec
bool	168721728.0 Ops/sec
keys	6442872.5 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to explain the provided benchmark and its test cases.

**Benchmark Purpose:**
The purpose of this benchmark is to compare the performance of different ways to check if an object has a property named "gr". This can be useful in scenarios where you need to iterate over the properties of an object or perform other operations that depend on whether a specific property exists.

**Test Cases:**

1. **undefined !== obj.gr;**: This test checks if the expression `obj.gr` is evaluated as falsey, which means it will return true if `obj.gr` is undefined or null.
2. **'undefined' !== typeof obj.gr;**: This test uses a type check to see if `typeof obj.gr` returns "undefined", which would indicate that `obj.gr` does not exist.
3. **'gr' in obj;**: This test uses the "in" operator to check if the property "gr" exists in the object `obj`.
4. **obj.hasOwnProperty( 'gr' );**: This test checks if the property "gr" is directly accessible on the `obj` object using its own hasOwnProperty method.
5. **!! obj.gr;**: This test uses a boolean cast to convert the value of `obj.gr` to a boolean, which will be true if it exists and false otherwise.
6. **Object.keys(obj).includes('gr');**: This test checks if the string "gr" is present in an array of object keys using the includes method.

**Performance Comparison:**

The benchmark compares the performance of each test case under different conditions. The results show that:

* `in` and `hasOwnProperty` are generally faster than type checks like `typeof`.
* Type checks can be fast if the property exists, but slower if it doesn't.
* Boolean casting (`!! obj.gr;`) is relatively slow compared to other methods.
* Using an array of object keys (`Object.keys(obj).includes('gr');`) is one of the slower methods.

**Interpretation:**
These results indicate that when checking for a property's existence, it's often faster and more efficient to use the "in" operator or directly access the property using its own hasOwnProperty method. Type checks like `typeof` can be useful if you're working with a specific type system, but may incur performance overhead.

When deciding which method to use, consider the trade-offs between speed, readability, and maintainability:

* Use `in` or `hasOwnProperty` when:
	+ You need to iterate over an object's properties.
	+ You want to avoid using type checks.
* Use `typeof` when:
	+ You're working with a specific type system that requires precise type checking.
	+ You want to emphasize the intent of your code (e.g., "does this property exist?").
* Avoid using boolean casting (`!! obj.gr;`) due to its relatively slow performance.

Keep in mind that these are general guidelines, and you should profile your specific use case to determine the most efficient approach.

Related benchmarks:

undefined vs. typeof vs. in vs. hasOwnProperty big object (version: 0)

Object lookup performance

Comparing performance of: undefined vs typeof vs in vs hasOwnProperty vs bool vs keys

Created: 6 years ago by: Guest

Jump to the latest result

undefined

typeof

in

hasOwnProperty

bool

keys

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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