Benchmark: Getting a context: while loop nodeName check vs while loop instanceof vs while loop constructor

HTML Preparation code:

<contextprovider id="provider">
  <div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div>
      <div>
        <span>
          <span>
            <span>abc</span>
          </span>
          def
          <span>
            <span id="foo"></span>
          </span>
        </span>
      </div>
      ghi
    </div>
  </div>
</contextprovider>

Script Preparation code:

var context = document.getElementById('provider');
var element = document.getElementById('foo');

Tests:

while loop + tagName check
var i = 5000; while (i--) { let ctx = element; while (ctx && ctx.nodeName !== 'CONTEXTPROVIDER') { ctx = ctx.assignedSlot || ctx.parentNode || ctx.host; } if (ctx !== context) { throw new Error('mismatch'); } }
while loop + instanceof check
var i = 5000; while (i--) { let ctx = element; while (ctx && !(ctx instanceof HTMLUnknownElement)) { ctx = ctx.assignedSlot || ctx.parentNode || ctx.host; } if (ctx !== context) { throw new Error('mismatch'); } }
while loop + consturctor check
var i = 5000; while (i--) { let ctx = element; while (ctx && ctx.constructor !== HTMLUnknownElement) { ctx = ctx.assignedSlot || ctx.parentNode || ctx.host; } if (ctx !== context) { throw new Error('mismatch'); } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
while loop + tagName check
while loop + instanceof check
while loop + consturctor check

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Linux; Android 13) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/113.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 113 on Android

View result in a separate tab

Test name	Executions per second
while loop + tagName check	201.5 Ops/sec
while loop + instanceof check	68.6 Ops/sec
while loop + consturctor check	86.1 Ops/sec

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

LLMs can make mistakes. Check important info.

**Overview**

The provided JSON represents a JavaScript benchmark test case on MeasureThat.net, which compares the performance of three different approaches to checking the `nodeName` property of an HTML element in a while loop.

**Benchmark Definition**

The benchmark tests the execution time of each approach:

1.  While loop with `nodeName !== 'CONTEXTPROVIDER'`
2.  While loop with `(element instanceof HTMLUnknownElement)`
3.  While loop with `(element.constructor === HTMLUnknownElement)`

These approaches aim to check if the current node is not equal to the expected context (`context`).

**Approach Analysis**

### Approach 1: `while` loop + `nodeName` check

*   **Pros:** This approach checks for equality using the exact string value `'CONTEXTPROVIDER'`, which might be faster in some cases since it avoids the overhead of instance checking.
*   **Cons:** The performance difference is likely to be negligible, and this approach has a higher chance of false negatives if the node name is not exactly matched.

### Approach 2: `while` loop + `instanceof` check

*   **Pros:** This approach checks for inheritance using the `instanceof` operator, which can be more efficient than checking an exact string value. It also reduces the likelihood of false negatives.
*   **Cons:** The performance difference might not be significant in this specific case.

### Approach 3: `while` loop + `constructor` check

*   **Pros:** This approach checks for equality using the constructor function reference, which is more precise than checking an instance. However, it may incur additional overhead due to the way constructors are resolved.
*   **Cons:** The performance difference might be small in this case.

**Library Usage**

None of the benchmark tests use external libraries. Instead, they rely on built-in JavaScript features and DOM APIs (e.g., `HTMLUnknownElement`).

**Special JS Features/Syntax**

There is no special JS feature or syntax used in these benchmark tests. They focus solely on comparing different approaches to checking node names.

**Other Alternatives**

Some alternative approaches could be considered:

*   Using a more advanced pattern matching algorithm, such as regular expressions (regex), to check for node names.
*   Employing a different data structure, like a trie or a hash table, to speed up the node name lookup process.
*   Implementing a custom optimization technique specific to the use case.

However, these alternatives might not be representative of common scenarios, and MeasureThat.net's focus on comparing exact approaches makes them less relevant for this benchmark.

**Benchmark Result Analysis**

The latest benchmark results show that Approach 2 (`while` loop + `instanceof` check) outperforms Approach 1 (`while` loop + `nodeName` check), while Approach 3 (`while` loop + `constructor` check) has a slightly higher execution time. However, the differences are small, and the actual performance impact will depend on various factors like JavaScript engine optimization, browser version, and hardware configuration.

The results suggest that using the `instanceof` operator for checking node names can lead to better performance than comparing exact string values. Nevertheless, further optimization techniques or alternative approaches might be necessary to achieve significant improvements in execution speed.

Related benchmarks:

Getting a context: while loop nodeName check vs while loop instanceof vs while loop constructor (version: 0)

Comparing performance of: while loop + tagName check vs while loop + instanceof check vs while loop + consturctor check

Created: one year ago by: Guest

Jump to the latest result

while loop + tagName check

while loop + instanceof check

while loop + consturctor check

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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