Using Lodash Groupby How To Add Your Own Keys For Grouped Output

Lodash is a powerful JavaScript library that provides a ton of useful functions to help you work with arrays, objects, strings, and more. One particularly handy function is `groupBy`, which allows you to group elements in an array based on a specified key or function. However, what if you want to add your own custom keys to the grouped output? That's where things get interesting!

To customize the keys in the grouped output using `groupBy` from Lodash, you can utilize the `_.mapKeys` function to transform the keys in the resulting object. This way, you can tailor the output to your specific requirements.

Let's dive into a practical example to see how you can achieve this. Suppose you have an array of objects representing different fruits, each with a name and a color. You want to group these fruits by color and then add a custom key to each group indicating the total number of fruits in that color.

Start by importing `groupBy` and `mapKeys` from Lodash:

const { groupBy, mapKeys } = require('lodash');

Next, define your array of fruits:

const fruits = [
  { name: 'Apple', color: 'Red' },
  { name: 'Banana', color: 'Yellow' },
  { name: 'Grape', color: 'Purple' },
  { name: 'Cherry', color: 'Red' },
  { name: 'Lemon', color: 'Yellow' }
];

Now, use the `groupBy` function to group the fruits by color:

const groupedFruits = groupBy(fruits, 'color');

At this point, `groupedFruits` will be an object where each key corresponds to a distinct color and the value is an array of fruits that share that color.

To add a custom key to each group indicating the total number of fruits, you can use `mapKeys`:

const result = mapKeys(groupedFruits, (value, key) => `${key}-total(${value.length})`);

In this example, we are transforming the keys of `groupedFruits` by appending a custom string that includes the original color key and the total number of fruits in that group. You can customize this logic based on your requirements.

Finally, you can log the `result` to see the modified output:

console.log(result);

By customizing the keys in the grouped output using `groupBy` and `mapKeys`, you have the flexibility to structure the data in a way that best suits your needs. Experiment with different transformations and key formats to tailor the output precisely to your requirements. This approach can make your code more readable and provide valuable insights into the grouped data.

In conclusion, with the power of Lodash's `groupBy` and `mapKeys`, adding your own keys for grouped output is a breeze. Give it a try in your projects and unlock new possibilities for organizing and analyzing your data!