how to use the unionwith function from the lodash library in typescript

To use the unionWith function from the Lodash library in TypeScript, follow the steps below:

1. Install Lodash as a dependency in your TypeScript project:

index.ts
npm install lodash
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2. Install Lodash's type definitions:

index.ts
npm install @types/lodash
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3. Import the unionWith function in your TypeScript file:

index.ts
import { unionWith } from 'lodash';
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4. Define the type of the comparator function:

index.ts
type Comparator<T> = (a: T, b: T) => boolean;
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5. Call the unionWith function, passing in the two arrays to combine and the comparator function:

index.ts
const array1 = [{ x: 1, y: 2 }, { x: 2, y: 3 }];
const array2 = [{ x: 1, y: 2 }, { x: 3, y: 4 }];
const comparator: Comparator<{ x: number; y: number }> = (a, b) => a.x === b.x && a.y === b.y;

const result = unionWith(array1, array2, comparator);
console.log(result); // [{ x: 1, y: 2 }, { x: 2, y: 3 }, { x: 3, y: 4 }]
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The unionWith function compares each element in both arrays using the provided comparator function. If the function returns true for two elements, only one of them will be included in the resulting array.