DynamicArray is a TypeScript utility for managing dynamic arrays with configurable focus, sorting, and key extraction. It provides methods to append items while maintaining the focus on a specific index. This package is designed to handle large arrays efficiently by reserving space and managing the array length dynamically.
You can install the package using npm:
npm install ts-dynamic-array
yarn add ts-dynamic-array
import { DynamicArray } from 'ts-dynamic-array';
const dynamicArray = new DynamicArray<number>({
reservedSize: 100,
maxLength: 50,
initialFocusIndex: 25,
onFocusedIndexChange: (index, lastIndex) => {
console.log(`Focus moved from ${lastIndex} to ${index}`);
},
sorter: (a, b) => a - b,
keyExtractor: (item) => item.toString(),
});
-
reservedSize
: Total size of the reserved array. This creates a very large array filled withnull
items initially. -
maxLength
: Maximum length of the array after adding new items. Ensures that the number of items with data never exceeds this limit, helping to save memory and avoid memory leaks. -
initialFocusIndex
: Index to focus on initially. -
onFocusedIndexChange
: Callback function invoked when the focus index changes. -
sorter
: Function to sort the items in the array. -
keyExtractor
: Function to extract the key from an item.
Appends new items to the array and optionally updates the focused index. The number of items with data will not exceed maxLength
.
dynamicArray.append([100, 101, 102]);
Sets the focused index.
dynamicArray.setFocusedIndex(10);
When you define reservedSize
as 10000 and maxLength
as 500, and append items to your DynamicArray, the number of items with data will never exceed 500. This is helpful for saving memory and avoiding memory leaks. When you append items, the positions (index) of previous items remain the same as before unless the index of items is affected by sorting.
const dynamicArray = new DynamicArray<number>({
reservedSize: 10000,
maxLength: 500,
initialFocusIndex: 5000,
sorter: (a, b) => a - b,
keyExtractor: (item) => item.toString(),
});
dynamicArray.append([6000, 6001, 6002]);
console.log(dynamicArray.array); // Large array with max 500 data items, rest are null
If you define reservedSize
as 1,000,000, the reserved memory for DynamicArray
will be approximately 3.81 MB. This estimation is based on each null
value occupying 4 bytes of memory.
Here is a table illustrating the memory usage for different reservedSize
values:
Reserved Size | Memory Usage (MB) |
---|---|
1,000 | 0.0038 |
10,000 | 0.038 |
100,000 | 0.381 |
1,000,000 | 3.81 |
10,000,000 | 38.1 |
const dynamicArray = new DynamicArray<number>({
reservedSize: 1_000_000,
maxLength: 500,
initialFocusIndex: 500_000,
sorter: (a, b) => a - b,
keyExtractor: (item) => item.toString(),
});
console.log(dynamicArray.array.length); // 1,000,000
The package includes tests to ensure the correct functionality of the DynamicArray class. You can run the tests using Jest.
npm test
This project is licensed under the MIT License.