Benchmark: Which is more efficient .replace() or .split().map().join()

Script Preparation code:

var testString = '052768194390675213483698521470';
function fakeBin(strNums){ 
  return strNums.split("")
                .map(num => num = num < 5 ? 0 : 1)
                .join("")
}
function fakeBin2(x) {
  return x.replace(/\d/g, n => "0000011111"[n])
}
function fakeBin3(word) {
  let result = '';
  for (var i = 0; i < word.length; i++) {
    result += Number(word[i]) < 5 ? 0 : 1;
  }
  return result;
}

Tests:

splitmapjoin
fakeBin(testString)
replace
fakeBin2(testString)
for
fakeBin3(testString)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
splitmapjoin
replace
for

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.127 Safari/537.36 OPR/60.3.3004.55692

Browser/OS: Opera 60 on Linux

View result in a separate tab

Test name	Executions per second
splitmapjoin	82727.7 Ops/sec
replace	38241.1 Ops/sec
for	176774.6 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation.

**Benchmark Overview**

The benchmark measures the efficiency of three different approaches for replacing or transforming a string: `String.prototype.replace()`, `Array.prototype.map()` followed by `Array.prototype.join()`, and a custom implementation using a `for` loop (`fakeBin3`). The test string is generated to contain a mix of digits, ensuring that both the replacement and transformation operations are applicable.

**Approach 1: String.prototype.replace()**

*   **Purpose:** Replaces all occurrences of one or more characters in a string with another specified character or value.
*   **Library Used:** JavaScript's built-in `String` object methods.
*   **Pros:**

*   Native, optimized for performance by the JavaScript engine.
    *   Easy to read and understand due to its simplicity and convention.
*   **Cons:**

*   May be slower than custom implementations, especially when dealing with large strings or complex patterns.
    *   Requires a string pattern to be specified.

**Approach 2: Array.prototype.map() followed by Array.prototype.join()**

*   **Purpose:** Applies a transformation function to each element of an array and returns a new array. The resulting array can then be converted back into a string using `Array.prototype.join()`.
*   **Library Used:** JavaScript's built-in `Array` object methods.
*   **Pros:**

*   More flexible than `String.prototype.replace()` when dealing with complex patterns or multiple replacements.
    *   Can handle non-string elements in the array, but may incur performance overhead due to type checking and boxing/unboxing.
*   **Cons:**

*   May be slower than custom implementations for simple replacement tasks.
    *   Requires an additional step to convert the resulting array back into a string.

**Approach 3: Custom Implementation using fakeBin3 (for loop)**

*   **Purpose:** Manually iterates through each character of the input string, applying the transformation based on a specified condition (`fakeBin3`).
*   **Library Used:** None (a custom implementation).
*   **Pros:**

*   Can be faster than `String.prototype.replace()` and the array-based approach for simple replacement tasks.
    *   Allows for fine-grained control over the transformation process, including handling non-string elements or complex patterns.
*   **Cons:**

*   More error-prone due to the need to manually handle edge cases and string manipulation.
    *   May require more code and be less readable than other approaches.

**Other Alternatives**

Some additional alternatives could include:

1.  Using `String.prototype.replace()` with a regular expression (`/\\d/g` in this case) for better performance on larger strings or complex patterns.
2.  Employing a different transformation function, such as using `Array.prototype.reduce()` instead of `Array.prototype.join()`.
3.  Leveraging modern JavaScript features like `template literals` or `Intl.NumberFormat` for more efficient and readable string manipulation.

In conclusion, the choice of approach depends on the specific requirements of the task, including performance, readability, and flexibility.

Related benchmarks:

Which is more efficient .replace() or .split().map().join() (version: 1)

Comparing performance of: splitmapjoin vs replace vs for

Created: 8 years ago by: Registered User

Jump to the latest result

splitmapjoin

replace

for

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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