Benchmark: char index vs charAt() vs slice() random access

Script Preparation code:

var str = 'foo bar baz';
var noop = Function.prototype;

Tests:

character index
let i = Math.random(10); if (str[i] == 'f') noop();
charAt()
let i = Math.random(10); if (str.charAt(i) == 'f') noop();
slice()
let i = Math.random(10); if (str.slice(i, i+1) == 'f') noop();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
character index
charAt()
slice()

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36

Browser/OS: Chrome 112 on Linux

View result in a separate tab

Test name	Executions per second
character index	1875404.4 Ops/sec
charAt()	6103941.5 Ops/sec
slice()	5697240.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what is being tested, compared, and the pros/cons of different approaches.

**Benchmark Definition**

The benchmark measures three ways to access a string's beginning character:

1. `char index`: Directly accessing the character at a specific index in the string.
2. `charAt()`: Using the `charAt()` method to get the character at a specific index in the string.
3. `slice()`: Using the `slice()` method to extract a single character from the string.

**Script Preparation Code**

The script preparation code is:
```javascript
var str = 'foo bar baz';
var noop = Function.prototype;
```
This sets up a test string and a no-op function, which is used as a placeholder for cases where no operation is performed when accessing the character.

**Html Preparation Code**

There is no HTML preparation code provided.

**Individual Test Cases**

The benchmark has three individual test cases:

1. **Character Index**
```javascript
let i = Math.random(10); if (str[i] == 'f') noop();
```
This test case directly accesses the character at a random index `i` in the string and checks if it's equal to `'f'`. The `noop()` function is called regardless of whether the condition is true or false.

2. **charAt()**
```javascript
let i = Math.random(10); if (str.charAt(i) == 'f') noop();
```
This test case uses the `charAt()` method to get the character at a random index `i` in the string and checks if it's equal to `'f'`. The `noop()` function is called regardless of whether the condition is true or false.

3. **slice()**
```javascript
let i = Math.random(10);  if (str.slice(i, i+1) == 'f') noop();
```
This test case uses the `slice()` method to extract a single character from the string starting at index `i` and checks if it's equal to `'f'`. The `noop()` function is called regardless of whether the condition is true or false.

**Latest Benchmark Result**

The latest benchmark result shows the execution speed for each test case on a Chrome 112 browser running on a Linux desktop. The results are:

1. `charAt()`: 6103941.5 executions per second
2. `slice()`: 5697240.0 executions per second
3. `char index`: 1875404.375 executions per second

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

* **Character Index**: Fastest, as it directly accesses the character without any method calls.
	+ Pros: Fastest execution speed, lowest overhead.
	+ Cons: May not work correctly if the string is modified or accessed concurrently.
* `charAt()`: Slower than direct indexing, but still relatively fast due to cache locality.
	+ Pros: More readable and maintainable code, handles string modifications well.
	+ Cons: Slightly slower execution speed compared to direct indexing.
* `slice()`: Slowest, as it involves creating a new array and iterating over the string.
	+ Pros: Handles string slicing and concatenation well, but not ideal for simple character access.
	+ Cons: Slowest execution speed, high overhead.

**Library/Function Used**

None of these approaches rely on a specific library or function. However, `charAt()` is a part of the String prototype in JavaScript, which provides a standardized way to access characters in a string.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntaxes used in this benchmark. The code only uses standard JavaScript constructs such as variables, functions, and conditional statements.

**Alternatives**

If you want to test other approaches for accessing a string's beginning character, you could consider:

* Using `indexOf()` instead of `charAt()`
* Creating a custom function to access the first character
* Using a library like Lodash or Ramda for functional programming

Keep in mind that each approach has its trade-offs, and the best choice depends on your specific use case and performance requirements.

Related benchmarks:

char index vs charAt() vs slice() random access (version: 0)

Compare methods for testing string's beggining character.

Comparing performance of: character index vs charAt() vs slice()

Created: one year ago by: Guest

Jump to the latest result

character index

charAt()

slice()

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):