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);
}

​x
 
// Array to hold the generated user datavar users = [];​// Function to generate random user datafunction 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)

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

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

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Experimental features:

Memory measurements supported only in Chrome.
For precise memory measurements Chrome must be launched with --enable-precise-memory-info flag.
More information: Monitoring JavaScript Memory

Test case name	Result
indexOf
startsWith

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/113.0.0.0 Safari/537.36

Browser/OS: Chrome 113 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
indexOf	148867.5 Ops/sec
startsWith	521624.7 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 7 months ago):

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:

indexOf with Array.filter
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:

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.
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:

Using indexOf with Array.filter
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:

Regular expressions: You can create custom regular expressions to match specific patterns in the city names.
**Array.map(): Instead of Array.filter(), use Array.map()` to create a new array with filtered results.
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.

LLMs can make mistakes. Check important info.

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: one year ago by: Guest

Jump to the latest result

indexOf

startsWith

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 7 months ago):