Tutorials

Lodash _.forEach() Collection Method

Posted in lodash Tutorial

Updated on Feb 24, 2024

By Mari Selvan

👁️ 47 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the vast landscape of JavaScript programming, efficient manipulation of collections is fundamental. Lodash, a feature-rich utility library, provides a suite of functions to simplify common tasks. Among these functions is the _.forEach() method, a versatile tool for iterating over elements in a collection.

This method enhances code readability and enables developers to perform actions on each item without the boilerplate of traditional loops.

🧠 Understanding _.forEach()

The _.forEach() method in Lodash is designed for iterating over elements in a collection, be it an array, object, or other iterable structures. It provides a clean and concise syntax for executing a function on each element, making it a powerful and time-saving construct.

💡 Syntax

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_.forEach(collection, iteratee)

collection: The collection to iterate over.
iteratee: The function invoked per iteration.

📝 Example

Let's explore a basic example to demonstrate the functionality of _.forEach():

example.js

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const _ = require('lodash');

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

_.forEach(numbers, (value, index) => {
    console.log(`Element at index ${index}: ${value}`);
});

In this example, the _.forEach() method is used to iterate over each element in the numbers array, logging the index and value to the console.

🏆 Best Practices

Leveraging Index or Key:

Take advantage of the second parameter in the iteratee function, which represents the index (for arrays) or key (for objects) of the current element. This information can be valuable when performing actions based on the element's position.
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```
const myObject = { a: 1, b: 2, c: 3 };

_.forEach(myObject, (value, key) => {
    console.log(`Key: ${key}, Value: ${value}`);
});
```

Early Termination:

If you need to break out of the loop based on a certain condition, you can use return false within the iteratee function to achieve early termination.

example.js

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

_.forEach(numbers, (value) => {
    if (value === 3) {
        console.log('Found 3! Stopping the loop.');
        return false;
    }
    console.log(`Processing: ${value}`);
});

Handling Edge Cases:

Consider edge cases, such as an empty collection. Implement appropriate checks to handle such scenarios and prevent potential errors.

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const emptyArray = [];

if (_.isEmpty(emptyArray)) {
    console.log('The array is empty. No elements to process.');
} else {
    _.forEach(emptyArray, (value) => {
        console.log(`This will not be executed for an empty array: ${value}`);
    });
}

📚 Use Cases

Data Transformation:

_.forEach() is excellent for transforming data within a collection. You can modify each element based on specific criteria without resorting to verbose loops.

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const prices = [10, 20, 30, 40];

const discountedPrices = [];
_.forEach(prices, (price) => {
    discountedPrices.push(price * 0.9); // Applying a 10% discount
});

console.log(discountedPrices);

DOM Manipulation:

In a browser environment, _.forEach() can simplify DOM manipulation tasks by iterating over elements and applying changes.
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```
const elements = document.querySelectorAll('.my-elements');

_.forEach(elements, (element) => {
    element.style.color = 'blue';
});
```

Asynchronous Operations:

_.forEach() can be used in scenarios where asynchronous operations need to be performed on each element of a collection.

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const asyncTasks = [/* ...array of asynchronous tasks... */];

_.forEach(asyncTasks, async (task) => {
    await task(); // Await asynchronous task completion
    console.log('Async task completed.');
});

🎉 Conclusion

The _.forEach() method in Lodash is a valuable tool for simplifying the iteration process over collections. Whether you are transforming data, manipulating the DOM, or dealing with asynchronous operations, _.forEach() provides a clean and concise syntax for handling common tasks.

Embrace the power of iteration with _.forEach() and streamline your JavaScript development!