Benchmark: typeof vs cached typeof (2 scans)

Script Preparation code:

var obj = {};

Tests:

uncached typeof
for (let n = 0; n < 1000; n++) { if (typeof obj === 'object') { if (typeof obj === 'object') { return true; } } }
cached typeof
for (let n = 0; n < 1000; n++) { const isObject = typeof obj; if (isObject) { if (isObject) { return true; } } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
uncached typeof
cached 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 break down the benchmark test case and explain what's being tested.

**Benchmark Overview**

The benchmark tests two approaches to check if an object is of type `object` in JavaScript:

1. **Uncached typeof**: This approach uses the built-in `typeof` operator without any caching optimizations.
2. **Cached typeof**: This approach uses a cached value for `typeof obj`, which is computed only once and reused across multiple iterations.

**What's being tested?**

The benchmark measures the performance difference between these two approaches:

* Execution time (measured in executions per second)
* Number of CPU cycles used
* Memory allocation

**Options compared:**

The benchmark compares the performance of two options:

1. **Uncached typeof**: Uses the `typeof` operator without caching optimizations.
2. **Cached typeof**: Uses a cached value for `typeof obj`, which is computed only once and reused across multiple iterations.

**Pros and Cons:**

* **Uncached typeof**:
	+ Pros: Simple to implement, widely supported by most JavaScript engines.
	+ Cons: May involve unnecessary computations or memory allocations if the object is not of type `object`.
* **Cached typeof**:
	+ Pros: Can reduce computation overhead and improve performance for repeated checks on an object's type.
	+ Cons: Requires additional memory allocation to store the cached value, which may increase memory usage.

**Other considerations:**

The benchmark also considers other factors that might affect performance:

* Cache locality: The order in which `typeof obj` is executed affects cache locality, as it can be executed multiple times within a single loop iteration.
* Loop overhead: The overhead of executing loops, including the number of iterations and any necessary synchronization.

**Library and special JS features:**

There are no libraries or special JavaScript features involved in this benchmark. However, note that modern browsers may use various optimization techniques, such as:

* JIT compilation
* Ahead-of-time compilation
* Just-In-Time (JIT) optimization

These optimizations can affect the performance of `typeof` operator but are not explicitly tested by this benchmark.

**Other alternatives:**

If you're interested in exploring alternative approaches to checking if an object is of type `object`, consider the following:

1. **Using a library**: There are libraries like `lodash.isObject()` that provide optimized implementations for checking object types.
2. **Using bitwise operations**: You can use bitwise operations to determine if an object is of type `object` by comparing its prototype chain length.

Keep in mind that these alternatives may have different performance characteristics and trade-offs compared to the benchmarked approaches.

Here's a sample code snippet demonstrating the uncached typeof approach:
```javascript
function isObject(obj) {
  for (let n = 0; n < 1000; n++) {
    if (typeof obj === 'object') {
      return true;
    }
  }
}
```
And here's a sample code snippet demonstrating the cached typeof approach:
```javascript
let cachedIsObject = null;

function isObject(obj) {
  const isObject = cachedIsObject || (cachedIsObject = typeof obj);
  for (let n = 0; n < 1000; n++) {
    if (isObject === 'object') {
      return true;
    }
  }
}
```

Related benchmarks:

typeof vs cached typeof (2 scans) (version: 0)

Comparing performance of: uncached typeof vs cached typeof

Created: 3 years ago by: Guest

Jump to the latest result

uncached typeof

cached 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):