Benchmark: isString vs - MeasureThat.net

Script Preparation code:

var x = "123"

Tests:

object prototype
var y = Object.prototype.toString.call(x) === '[object String]'
typeof
var y = typeof x === "string"

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
object prototype
typeof

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
object prototype	11638947.0 Ops/sec
typeof	31891918.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark and its various aspects.

**What is being tested?**

The provided JSON represents a JavaScript microbenchmarking test case on MeasureThat.net. The goal of this test is to compare two different methods for determining whether a variable `x` is a string in JavaScript:

1. **Using `Object.prototype.toString.call(x)`**: This method checks if the object's prototype is a String object, which indicates that the variable `x` is indeed a string.
2. **Using `typeof x === "string"`**: This method uses the `typeof` operator to check the type of the variable `x`. If it returns `"string"`, then `x` is considered a string.

**Options comparison**

The two options being compared are:

* **Option 1: Using `Object.prototype.toString.call(x)`**
	+ Pros:
		- This method is more accurate because it checks if the object's prototype is a String object, which is a more precise way to determine string type.
	+ Cons:
		- It may be slower due to the overhead of calling `toString()` and checking the prototype chain.
* **Option 2: Using `typeof x === "string"`**
	+ Pros:
		- Faster execution speed because it only requires a single operation (the `typeof` operator).
	+ Cons:
		- Less accurate because it relies on the JavaScript engine's implementation of the `typeof` operator, which may not always return the correct result.

**Other considerations**

When choosing between these two options, developers should consider factors such as:

* Performance-critical code: If speed is crucial, using `typeof x === "string"` might be a better choice. However, if accuracy is more important and performance isn't a concern, using `Object.prototype.toString.call(x)` would be the safer option.
* Code readability and maintainability: Using `typeof x === "string"` can make code easier to read and understand for developers who are familiar with JavaScript's type checking conventions.

**Library usage**

In this benchmark, there is no explicit library being used. However, the `Object.prototype.toString()` method relies on the `String` prototype object, which is a built-in part of the JavaScript language.

**Special JS feature or syntax**

There is no special JavaScript feature or syntax mentioned in the provided JSON data.

**Benchmark preparation code**

The benchmark preparation code is straightforward:
```javascript
var x = "123";
```
This code simply assigns a string value to the variable `x`.

Now that we've explained the test, let's take a look at how it compares between different browsers.

According to the latest benchmark result:

* **Chrome 122**: Both methods produce similar results, with `typeof x === "string"` being slightly faster (11638947.0 executions per second) and more accurate.
* **Other browsers** are not shown in this example.

As for alternative approaches, some other options could be explored:

* Using a dedicated string type or function, such as `String()` or `String.prototype.isPrototypeOf()`.
* Implementing custom string type checking using bitwise operations (e.g., using a bit mask to check if a value is a string).
* Using a library like Lodash, which provides utility functions for working with strings.

However, these alternatives would likely introduce additional complexity and overhead, making them less suitable for performance-critical code.

Related benchmarks:

isString vs (version: 0)

Comparing performance of: object prototype vs typeof

Created: 2 years ago by: Guest

Jump to the latest result

object prototype

typeof

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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