Benchmark: Direct property lookup vs in vs typeof

Script Preparation code:

var host = {
    method: function() {
        console.log('method is invoked');
    }
}

Tests:

Check via direct property lookup
if(host.method) { console.log('method exists'); }
Check via in
if('method' in host) { console.log('method exists'); }
Check via typeof
if(typeof host['method'] !== 'undefined') { console.log('method exists'); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Check via direct property lookup
Check via in
Check via typeof

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**What is being tested?**

The benchmark measures the performance difference between three approaches to check if a property exists on an object:

1. **Direct Property Lookup**: `if(host.method) { ... }`
2. **Using the `in` operator**: `'method' in host { ... }`
3. **Using the `typeof` operator with the dot notation**: `if(typeof host['method'] !== 'undefined') { ... }`

These approaches are used to check if a property exists on an object.

**Options compared**

The benchmark compares the performance of these three approaches. The choice of approach depends on various factors, including:

* **Readability and conciseness**: Direct Property Lookup is often considered more readable and concise.
* **Performance**: Using `in` or `typeof` can be faster than direct property lookup for certain use cases.
* **Browser support**: Some older browsers may not support the `in` operator.

**Pros and Cons of each approach**

1. **Direct Property Lookup (`if(host.method) { ... }`)**
	* Pros: More readable, concise, and often preferred in modern JavaScript.
	* Cons: May be slower for certain use cases due to the overhead of property access.
2. **Using the `in` operator (`'method' in host { ... }`)**
	* Pros: Can be faster than direct property lookup, as it avoids the overhead of property access.
	* Cons: Less readable and more verbose, may not work in older browsers that don't support `in`.
3. **Using the `typeof` operator with the dot notation (`if(typeof host['method'] !== 'undefined') { ... }`)**
	* Pros: Can be faster than direct property lookup, as it avoids the overhead of property access.
	* Cons: Less readable and more verbose, may not work in older browsers that don't support `typeof` with bracket notation.

**Library usage**

There is no library explicitly mentioned in the benchmark code. However, some libraries like Lodash or Ramda might use these approaches internally for certain operations.

**Special JavaScript features/syntax**

None of the provided test cases use any special JavaScript features or syntax beyond what's standard in modern browsers.

**Other alternatives**

If you're interested in exploring alternative approaches, consider:

* Using `hasOwnProperty()` on objects: `if(host.hasOwnProperty('method')) { ... }`
* Using a library like `fast-assert` or `jest-matchers` for more expressive and concise assertions.
* Investigating the performance impact of other property access methods, such as `in` with bracket notation (`'method' in host[Symbol.iterator]`)

Related benchmarks:

Direct property lookup vs in vs typeof (version: 1)

Comparing performance of: Check via direct property lookup vs Check via in vs Check via typeof

Created: 4 years ago by: Registered User

Jump to the latest result

Check via direct property lookup

Check via in

Check via typeof

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):