Benchmark: startsWith vs indexOf with Array.filter for user dataset

Script Preparation code:

// Array to hold the generated user data
var users = [];

// Function to generate random user data
function generateUserData() {
  const names = ['John', 'Jane', 'Mike', 'Emily', 'David', 'Sarah', 'Chris', 'Jessica', 'Mark', 'Lisa'];
  const lastNames = ['Smith', 'Johnson', 'Williams', 'Brown', 'Jones', 'Miller', 'Davis', 'Garcia', 'Rodriguez', 'Wilson'];
  const cities = ['New York', 'Los Angeles', 'Chicago', 'Houston', 'Phoenix', 'Philadelphia', 'San Antonio', 'San Diego', 'Dallas', 'San Jose'];
  
  const name = names[Math.floor(Math.random() * names.length)];
  const lastName = lastNames[Math.floor(Math.random() * lastNames.length)];
  const age = Math.floor(Math.random() * 60) + 18; // Random age between 18 and 77
  const city = cities[Math.floor(Math.random() * cities.length)];
  
  return {
    name,
    lastName,
    age,
    city,
  };
}

for (let i = 0; i < 500; i++) {
  const user = generateUserData();
  users.push(user);
}

Tests:

indexOf
const usersInSanCities = users.filter(user => user.city.indexOf('San') === 0)
startsWith
const usersInSanCities = users.filter(user => user.city.startsWith('San'))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
indexOf
startsWith

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the provided benchmark definition and test cases to understand what is being tested.

**Benchmark Definition:**

The benchmark measures the performance difference between two approaches:

1. `indexOf` with `Array.filter`
2. `startsWith` (using the `startsWith` method on strings)

The benchmark creates an array of 500 user objects, each representing a person with a random name, last name, age, and city.

**Test Cases:**

There are two test cases:

1. **`indexOf`**: The first test case uses the `indexOf` method to filter users whose city starts with 'San'. This approach is likely more common in older JavaScript versions.
2. **`startsWith`**: The second test case uses the `startsWith` method to achieve the same result as the first test case.

**Options Compared:**

The benchmark compares two options:

1. Using `indexOf` with `Array.filter`
2. Using `startsWith`

**Pros and Cons of Each Approach:**

**`indexOf`:**

Pros:

* Wide compatibility across older JavaScript versions
* Can be used for other purposes beyond filtering arrays

Cons:

* Generally slower than modern methods like `startsWith` due to its substring search algorithm
* May not be as efficient when dealing with large datasets or complex filters

**`startsWith`:**

Pros:

* Faster execution times, especially for larger datasets or more complex filters
* More concise and readable code
* Available in most modern JavaScript versions

Cons:

* Limited compatibility compared to older versions of JavaScript that don't support `startsWith`
* May not be suitable for all use cases where substring search is required

**Library/Functionality:**

Neither the `indexOf` nor `startsWith` methods are part of a specific library. They are built-in functions in JavaScript.

**Special JS Feature/Syntax:**

The `startsWith` method was introduced in ECMAScript 2015 (ES6) and has been supported by most modern browsers and Node.js versions since then.

**Other Considerations:**

* The benchmark measures the performance difference between these two approaches. However, other factors like code readability, maintainability, and compatibility might also be important considerations.
* The use of `Array.filter` is a common pattern in JavaScript programming, but it may not always be the most efficient way to filter arrays.

**Alternative Approaches:**

If you need more control over the filtering process or want to optimize performance further, consider using:

1. **Regular expressions**: You can create custom regular expressions to match specific patterns in the city names.
2. **Array.map()`: Instead of `Array.filter()`, use `Array.map()` to create a new array with filtered results.
3. **Other filtering methods**: Depending on your specific requirements, you might want to explore other filtering techniques like using `indexOf()` in combination with `Array.prototype.slice()` or utilizing libraries like Lodash.

Keep in mind that these alternatives may have different trade-offs and requirements depending on your specific use case.

Related benchmarks:

startsWith vs indexOf with Array.filter for user dataset (version: 0)

Comparing performance of: indexOf vs startsWith

Created: 2 years ago by: Guest

Jump to the latest result

indexOf

startsWith

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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