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Frontend Development for Flask Web App: Simplified


What is the Front End for Flask App?

The front end for a Flask app refers to the user interface that users interact with in their web browsers. It is responsible for displaying the content and functionality of the app, allowing users to input data, view results, and interact with the app seamlessly.

In the context of a Python Flask app, the front end is typically built using HTML, CSS, and JavaScript. Flask serves as the back end, handling requests and providing the necessary data to the front end for rendering. The front end and back end work together to create a complete web application.

React Explained

React is a JavaScript library that is frequently used for building user interfaces. It is a powerful and versatile library that can be easily integrated into a Flask app. Unlike other client-side MVC frameworks, React does not make assumptions about the tech stack, making it flexible for use with different back end frameworks.

React focuses on the user interface (UI) of an application, managing specific areas rather than the entire UI. It uses a hierarchical structure of modular view components to define the UI. These components combine static markup with dynamic JavaScript to create reusable and flexible UI elements.

Components in React are similar to directives in AngularJS. They are defined using JSX, an XML-like syntax that transcompiles to JavaScript. React uses a virtual DOM to efficiently update only the necessary parts of the UI when the state changes, resulting in fast rendering speeds.

To get started with React, you can refer to the official React documentation, which provides a comprehensive guide on how to use React in your applications.

Project Setup

To showcase the use of React in a Flask app, we will use a Flask boilerplate code provided in the repository. Follow these steps to set up the project:

  1. Download the boilerplate code from the given repository link.
  2. Extract the files from the downloaded zip archive.
  3. Create and activate a virtual environment for the project.
  4. Install the project dependencies by running the following command: pip install -r requirements.txt.
  5. Start the Flask app using the provided run script: sh

With these steps, you will have the Flask app running and ready to integrate React into the front end.

React - Round One

In this section, we will explore a simple React component and add it to our Flask app. The following steps explain the process:

The Component: Moving from Static to React

  1. Open the hello.html file in your project.
  2. Add the following script inside the <script> tag:
<script type="text/jsx">
/*** @jsx React.DOM */
var realPython = React.createClass({
render: function() {
React.createElement(realPython, null),

This script defines a React component called realPython that renders a greeting message inside an h2 element. The ReactDOM.render function is used to mount the component onto the DOM by targeting the element with the id content.

With this script added to the hello.html file, the Flask app will render the React component in the specified location on the front end.


In this tutorial, we explored the front end for a Flask app and how React can be integrated into it. We learned about the basic concepts of React and its role in managing the UI of an application. We also set up a Flask project and added a simple React component to the front end.

By leveraging the power of React, developers can create dynamic and interactive user interfaces for their Flask apps, enhancing the overall user experience. Remember to refer to the official React documentation for more in-depth knowledge on using React in your projects.