Benchmark: leftPad vs nativeLeftPad

Tests:

nativeLeftPad
function nativeLeftPad(string, len, ch) { return string.padStart(len, ch); } nativeLeftPad('abcdefg', 10, '0')
leftPad
function leftPad(str, len, ch) { let new_str = `${ch.repeat(len)}${str}`; return new_str.slice(-len); } leftPad('abcdefg', 10, '0')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
nativeLeftPad
leftPad

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Windows

View result in a separate tab

Test name	Executions per second
nativeLeftPad	10811108.0 Ops/sec
leftPad	8941133.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark definition is a JSON object that describes two JavaScript functions: `nativeLeftPad` and `leftPad`. The purpose of these functions is to pad a given string with a specified character (or characters) to achieve a certain length.

**Options Being Compared**

The two options being compared are:

1. **Native `padStart()` method**: This is a built-in JavaScript method that pads a string with a specified character (or characters) on the left until it reaches a specified length.
2. **Custom `leftPad()` function**: This function takes three arguments: the input string, the desired padding length, and the character(s) to use for padding.

**Pros and Cons**

Here are some pros and cons of each approach:

**Native `padStart()` method**

Pros:

* Efficient: Built-in methods like `padStart()` are optimized for performance.
* Portable: Works across different browsers and environments without modifications.

Cons:

* Limited control: The resulting string is always padded with the same character(s) on the left.
* Potential security risks: If used with untrusted input, this method can lead to injection vulnerabilities.

**Custom `leftPad()` function**

Pros:

* Customizable: Allows for more control over the padding process and potential for optimization.
* Secure: By explicitly choosing the padding characters, you can mitigate security risks associated with untrusted input.

Cons:

* Inefficient: Implementing a custom solution can lead to slower performance compared to built-in methods.
* Less portable: Requires modifications to work across different browsers and environments.

**Other Considerations**

When designing or using these functions, consider the following factors:

* Input validation: Ensure that input strings are properly sanitized and validated to prevent security risks.
* Padding character selection: Choose padding characters carefully to achieve the desired effect while minimizing potential issues (e.g., null or undefined characters).

**Library Usage**

Neither of the provided functions uses any external libraries. The `padStart()` method is a built-in JavaScript function, while the custom `leftPad()` function does not rely on any third-party libraries.

**Special JS Features/Syntax**

There are no special JavaScript features or syntax used in these benchmarks. They only employ basic string manipulation and control flow constructs (if/else statements).

Now that we've dissected the benchmark, here are some alternative approaches you could consider:

1. **Using `toString()` with a padding string**: You can use the `toString()` method to concatenate the input string with a padding string of desired length. This approach provides more control over the padding process but may be less efficient than using `padStart()`.
2. **Employing string interpolation**: String interpolation techniques, like template literals (`${}`), could be used to create a padded string. However, this might not be as straightforward or performance-friendly as using built-in methods.
3. **Exploring other padding methods**: Depending on your specific requirements, you may need to explore alternative padding methods, such as using `Array.prototype.fill()` or working with buffer types.

These alternatives can help you better understand the strengths and weaknesses of different approaches when implementing string padding in JavaScript.

Related benchmarks:

leftPad vs nativeLeftPad (version: 0)

Comparing performance of: nativeLeftPad vs leftPad

Created: 3 years ago by: Registered User

Jump to the latest result

nativeLeftPad

leftPad

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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