Benchmark: string[index] vs charAt(index) vs charCodeAt(index)

Script Preparation code:

const PERIOD = '.';
const SINGLE_QUOTE = "'";
const DOUBLE_QUOTE = '"';
const BACK_TICK = '`';

function getPartsWithStringIndex(text) {
    const parts = [];
    let path;
    let partStart = 0;
    let partEnd = -1;
    let quotedWith = null;
    let previous;
    let current;
    for (let index = 0; index <= text.length; index++) {
        previous = current;
        current = text[index];

        if (index === partStart) {
            if (current === DOUBLE_QUOTE || current === SINGLE_QUOTE || current === BACK_TICK) {
                quotedWith = current;
                continue;
            }
        }
        if (typeof current === 'undefined' ||
            (current === PERIOD && (!quotedWith || previous === quotedWith))) {
            partEnd = index;
        }
        if (partStart < partEnd) {
            if (quotedWith) {
                path = text.substring(partStart + 1, index - 1);
                quotedWith = null;
            } else {
                path = text.substring(partStart, index);
            }
            parts.push({
                path
            });
            partStart = index + 1;
        }
    }

    return parts;
}

function getPartsWithCharAt(text) {
    const parts = [];
    let path;
    let partStart = 0;
    let partEnd = -1;
    let quotedWith = null;
    let previous;
    let current;
    for (let index = 0; index <= text.length; index++) {
        previous = current;
        current = text.charAt(index);

        if (index === partStart) {
            if (current === DOUBLE_QUOTE || current === SINGLE_QUOTE || current === BACK_TICK) {
                quotedWith = current;
                continue;
            }
        }
        if (current === '' ||
            (current === PERIOD && (!quotedWith || previous === quotedWith))) {
            partEnd = index;
        }
        if (partStart < partEnd) {
            if (quotedWith) {
                path = text.substring(partStart + 1, index - 1);
                quotedWith = null;
            } else {
                path = text.substring(partStart, index);
            }
            parts.push({
                path
            });
            partStart = index + 1;
        }
    }

    return parts;
}
const PERIOD_CODE = '.'.charCodeAt(0);
const SINGLE_QUOTE_CODE = "'".charCodeAt(0);
const DOUBLE_QUOTE_CODE = '"'.charCodeAt(0);
const BACK_TICK_CODE = '`'.charCodeAt(0);

function getPartsWithCharCodeAt(text) {
    const parts = [];
    let path;
    let partStart = 0;
    let partEnd = -1;
    let quotedWith = null;
    let previous;
    let current;
    for (let index = 0; index <= text.length; index++) {
        previous = current;
        current = text.charCodeAt(index);

        if (index === partStart) {
            if (current === DOUBLE_QUOTE_CODE ||
                current === SINGLE_QUOTE_CODE ||
                current === BACK_TICK_CODE) {
                quotedWith = current;
                continue;
            }
        }
        if (isNaN(current) || (current === PERIOD_CODE && (!quotedWith || previous === quotedWith))) {
            partEnd = index;
        }
        if (partStart < partEnd) {
            if (quotedWith) {
                path = text.substring(partStart + 1, index - 1);
                quotedWith = null;
            } else {
                path = text.substring(partStart, index);
            }
            parts.push({
                path
            });
            partStart = index + 1;
        }
    }

    return parts;
}
var testCases = [
    // subset of cases
    'path.to.a.value',
    'pathTo.someSpecified.aValue',
    'path."with `inner` quoted"."`parts`"',
    'path."with spaces"."to a value"',
    'path."with.dots"."to.a.value"'
]
var partsCount = 0

Tests:

String[index]
partsCount = 0 for (const testCase of testCases) { const parts = getPartsWithStringIndex(testCase) partsCount += parts.length } if (partsCount !== 16) throw new Error('String[index] invalid parts count ' + partsCount)
String.charAt(index)
partsCount = 0 for (const testCase of testCases) { const parts = getPartsWithCharAt(testCase) partsCount += parts.length } if (partsCount !== 16) throw new Error('String[index] invalid parts count ' + partsCount)
String.charCodeAt(index)
partsCount = 0 for (const testCase of testCases) { const parts = getPartsWithCharCodeAt(testCase) partsCount += parts.length } if (partsCount !== 16) throw new Error('String[index] invalid parts count ' + partsCount)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
String[index]
String.charAt(index)
String.charCodeAt(index)

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/124.0.0.0 Safari/537.36

Browser/OS: Chrome 124 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
String[index]	486513.8 Ops/sec
String.charAt(index)	375268.0 Ops/sec
String.charCodeAt(index)	58410.3 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 benchmark and its various components.

**Benchmark Overview**

The benchmark compares three different approaches to extract parts from a string:

1. `String[index]`
2. `String.charAt(index)`
3. `String.charCodeAt(index)`

These methods are used to parse strings by extracting individual parts, such as values or quoted substrings, using a specific index or character.

**Methods Overview**

Each method has its own way of parsing the string:

*   `String[index]`: This method uses bracket notation (`[index]`) to access and extract characters from the string. It returns the value at that index.
*   `String.charAt(index)`: Similar to `String[index]`, but this method explicitly calls the `charAt()` function to get the character at the specified index.
*   `String.charCodeAt(index)`: This method uses the ASCII code of a character (i.e., its Unicode code point converted to an integer value between 0 and 127) to extract characters from the string. It returns the Unicode code point at that index.

**Test Cases**

The benchmark consists of four test cases:

1.  `partsCount = 0` followed by `for (const testCase of testCases)` ... Each loop iterates over a subset of test cases and calls the respective parsing method (`String[index]`, `String.charAt(index)`, or `String.charCodeAt(index)`) to extract parts from each test case.
2.  The extracted parts are then counted using the variable `partsCount`.
3.  After all iterations, if the expected number of parts (16) is not equal to the actual count (`partsCount`), an error message will be thrown.

**Results**

The benchmark results display data for each of three test cases:

*   Each row contains information about a specific browser instance, including its raw user agent string, browser version, device platform, operating system, and executions per second.
*   The `TestName` field corresponds to the respective parsing method being tested.

**Benchmark Implications**

In summary, this benchmark evaluates three different methods for extracting parts from strings:

1.  **Efficiency**: Which method is faster? Does it prioritize execution speed over accuracy or vice versa?
2.  **Robustness**: How well do these methods handle edge cases or malformed input data?
3.  **Browser Support**: Are the parsing methods universally supported across different browsers and platforms?

**Potential Optimization Opportunities**

Considering the parsing methods used, potential optimizations for performance enhancements:

*   Implementing more efficient indexing or substring extraction techniques (e.g., string slicing, regular expressions) might lead to better performance.
*   Considering caching mechanisms to store precomputed results could speed up repeated computations.

Feel free to ask me any specific follow-up questions.

Related benchmarks:

string[index] vs charAt(index) vs charCodeAt(index) (version: 1)

Compare same algorithm using javascript String[index] vs String.charAt(index) vs String.charCodeAt(index)

Comparing performance of: String[index] vs String.charAt(index) vs String.charCodeAt(index)

Created: 3 years ago by: Registered User

Jump to the latest result

String[index]

String.charAt(index)

String.charCodeAt(index)

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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