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

To use the flattendepth function from the Lodash library in TypeScript, you first need to install both Lodash and its type definitions using npm:

index.ts
npm install lodash @types/lodash
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Once you have installed Lodash and its type definitions, you can import the flattendepth function and use it in your TypeScript code like this:

index.ts
import * as _ from "lodash";

const array = [1, [2, [3, [4]], 5]];

const flatArrayDepth2 = _.flattenDepth(array, 2);
console.log(flatArrayDepth2); // [1, 2, 3, [4], 5]
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In this example, we import Lodash as _ and use the flattenDepth function to flatten the array to a depth of 2, which means that subarrays up to two levels deep will be flattened, while subarrays deeper than 2 levels will remain untouched.

Note that we use the Lodash function syntax _.flattenDepth(array, depth) to call flattendepth. The depth parameter is optional, and if omitted, it defaults to 1. If you only need to flatten a single level deep, you can simplify the code by using the _.flatten function instead.