Benchmark: Finding items in array

Script Preparation code:

var items = []

for(var i = 0; i < 1000; i++) {
    items.push({id: i + 1})
}

var findItem = 523

Tests:

for
var index = -1 for(var i = 0; i < items.length; i++) { if(items[i].id === findItem) { index = i; break; } }
findIndex
items.findIndex(item => item.id === findItem)
find
items.find((a) => a.id === findItem)
reduce
items.reduce((acc, obj, i) => (obj.id === findItem) ? acc.concat(i) : acc, [])
filter
items.filter(function (element) { return element.id === findItem; });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
findIndex
find
reduce
filter

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark and the options being compared.

**Benchmark Goal:**
The goal of this benchmark is to measure how efficiently JavaScript arrays can be searched for a specific item.

**Prepared Script:**
Before running the tests, a script prepares an array with 1000 items, each having an `id` property. The `findItem` variable is set to the value `523`, which will be used to search for in the array.

**Comparison Options:**
The benchmark compares four different methods to find the item in the array:

1. **For Loop**: A traditional loop that iterates over the array elements and checks each one's `id` property.
2. **findIndex()**: A method introduced in ECMAScript 2015 (ES6) that returns the index of the first element in the array that satisfies the provided testing function.
3. **find()**: Another ES6 method that returns the value of the first element in the array that satisfies the provided testing function.
4. **reduce()**: A method that applies a reduction function to each element in the array, returning an accumulator that is updated with the value of the first element that satisfies the testing function.

**Pros and Cons:**

*   **For Loop**: Pros: Can be used for complex searches or when no specific index is required. Cons: Time-consuming due to the iterative approach.
*   **findIndex()**: Pros: Fast and efficient, returns the exact index of the found element. Cons: May not work well with arrays that have a large number of unique elements.
*   **find()**: Pros: Convenient for simple searches and returns the found value. Cons: Returns `undefined` if no match is found, which may lead to errors in the code. Also, it stops iterating as soon as it finds the first match, whereas findIndex will iterate until it finds the last match.
*   **reduce()**: Pros: Can be used for more complex reductions or accumulating values. Cons: Requires the accumulator and reduction function to be defined upfront, which can make the code harder to read.

**Library Usage:**
None of the provided benchmarks use any external libraries. However, some libraries like Lodash might offer similar functionality using their own utility functions (e.g., `_.findIndex()` or `_._find()`).

**Special JS Features/Syntax:**
ES6 features and syntax are used throughout the benchmark:

*   Arrow functions (`=>`) in the `findIndex` and `find` tests.
*   Template literals (`\r\n`) in the script preparation code.

**Alternatives:**

*   Other ES6 methods like `includes()`, which returns a boolean indicating whether an element with the specified value exists in the array, or `some()` and `every()`, which perform logical operations on elements in the array.
*   External libraries like Lodash (as mentioned earlier) provide additional utility functions for array manipulation.
*   Native methods like `indexOf()` or `lastIndexOf()` can be used instead of `findIndex`.
*   Manual looping with traditional JavaScript (`for` loops, `while` loops, etc.) would be slower and less efficient.

In conclusion, the benchmark compares four common methods to search for an item in a JavaScript array. Understanding the trade-offs between these methods can help developers choose the most suitable approach for their specific use cases.

Related benchmarks:

Finding items in array (version: 0)

Comparing performance of: for vs findIndex vs find vs reduce vs filter

Created: 6 years ago by: Guest

Jump to the latest result

for

findIndex

find

reduce

filter

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):