Home Arrow Icon Knowledge base Arrow Icon Global Arrow Icon What are the memory implications of using push vs concat
    JavaScript push vs concat array methods memory usage performance state management React immutability array operations


What are the memory implications of using push vs concat


The memory implications of using `push` vs `concat` in JavaScript arrays depend on several factors:

Memory Usage

1. Concat:
- Memory Usage: Creates a new array, which can lead to significant memory usage, especially for large arrays.
- Example: Concatenating two arrays of size 10,000 each, `concat` performs at 0.40 ops/sec, while `push` performs at 378 ops/sec.

2. Push:
- Memory Usage: Modifies the original array in-place, which is generally faster and more memory-efficient.
- Example: Pushing elements from one array to another, `push` performs significantly faster than `concat`.

Performance Benchmarks

1. Concat:
- Slow: Creates a new array, which can lead to significant memory usage and slower performance, especially for large arrays.
- Example: Concatenating two arrays of size 10,000 each, `concat` performs at 0.40 ops/sec, while `push` performs at 378 ops/sec.

2. Push:
- Fast: Modifies the original array in-place, which is generally faster and more memory-efficient.
- Example: Pushing elements from one array to another, `push` performs significantly faster than `concat`.

Immutability and State Management

1. Immutability:
- Concat: Ensures immutability by creating a new array, which is essential for state management in React and other applications.
- Push: Mutates the original array, which can lead to unexpected behavior and bugs.

2. State Management:
- React: Uses immutability to ensure that state changes are properly detected and re-rendered. `concat` ensures immutability, making it suitable for state updates in React.

Best Practices

1. Use `concat` for State Updates:
- When updating state in React, use `concat` to ensure immutability and avoid unexpected behavior.

2. Use `push` for Performance:
- For performance-critical applications, use `push` to modify the original array in-place.

3. Avoid Mutating State:
- Avoid mutating state directly using methods like `push` or `splice`. Instead, create a new state object with the updated values.

Edge Cases

1. Concat vs. Push for Large Arrays:
- Concat: Can be faster if the destination array has enough space to accommodate the new elements without needing to resize the array.
- Push: Can be slower if the destination array needs to be resized to accommodate the new elements.

2. Edge Cases with `apply`:
- Concat with `apply`: Can be slower due to the additional overhead of creating a new array and copying elements.
- Push with `apply`: Can be faster if the destination array is large and the new elements are added at the end.

Conclusion

In summary, when it comes to large arrays, `push` is generally faster and more memory-efficient, while `concat` ensures immutability. The choice between the two methods depends on the specific requirements of your application, including performance, state management, and immutability.

Citations:
[1] https://codeburst.io/jsnoob-push-vs-concat-basics-and-performance-comparison-7a4b55242fa9?gi=a762849790fe
[2] https://dev.to/uilicious/javascript-array-push-is-945x-faster-than-array-concat-1oki
[3] https://dev.to/uilicious/javascript-array-push-is-945x-faster-than-array-concat-1oki/comments
[4] https://phuoc.ng/collection/this-vs-that/concat-vs-push/
[5] https://stackoverflow.com/questions/25339803/javascript-concat-vs-push-benchmark