title: Introduction layout: docs category: docs order: 1

Introduction

Figwheel was a pioneer in hot-reloading and provides remarkably fast workflow for a compile-to-JavaScript language, several of its features are now common in other tools.

Features

Figwheel is more than a simple wrapper around the ClojureScript compiler. Figwheel compiles more than 4 years of thought, reflection and user feedback into its codebase.

Figwheel provides a slew of features in the name of providing better ClojureScript experience.

• fast intelligent hot-reloading
• heads up display with compiler feedback
• parsed error messages with code context
• informative configuration errors
• minimal configuration
• great REPL experience
• Nodejs support
• built-in server to get started quickly
• helper application to provide contextual help
• live CSS reloading
• simplicity of only being a library
• minimal dependencies
• grokable codebase
• works equally well with Leiningen and Clojure CLI Tools

Figwheel Main vs. lein figwheel

You are currently looking at documentation for Figwheel Main which is the latest iteration of Figwheel. The original lein-figwheel is still relevant and widely used.

Figwheel Main is a complete re-write of lein-figwheel and the following advantages:

Starts faster

The Figwheel Main codebase is much smaller. A lot of attention was placed on minimizing dependencies and as a result it starts much faster.

REPL connection

Figwheel Main's REPL evaluates on just one connected JavaScript client whereas lein-figwheel's REPL evaluated on all connected clients with the same build-id.

Figwheel Main's REPL will let you select which client environment to use when you have multiple connected clients.

Minimal configuration

Figwheel main makes intelligent choices for your ClojureScript compiler options. This allows you to get started with very little configuration.

Provides a cljs.main CLI interface

Utilizing the same CLI from cljs.main saves you from having to learn yet another way to compile ClojureScript. It's a design goal to keep the experience consistent between the two tools.

The CLI is also much more expressive than lein-figwheel, which translates into less configuration. The CLI will allow you to create test builds and deployment builds without needing a separate configuration for each build.

Better Nodejs experience

With Figwheel Main you can go from zero to a fully hot reloading Node workflow with very little configuration. Figwheel Main also starts a Node process for you when you launch a build.

Simpler codebase

Figwheel Main has a much smaller codebase. It is more approachable and forgiving when one wants to understand how it works.

much more

ClojureScript, Clojure and the wider ecosystem have all changed over the last 4 years. Another thing that has changed is my understanding of how to write a Clojure tool. Figwheel Main incorporates the influences of all these changes and the result is a fundamentally different codebase with too many improvements to list here.

Why not just incorporate these changes into lein-figwheel?

It would be impossible to incorporate all the changes presented in Figwheel Main while maintaining backwards compatibility with lein-figwheel.

About this Document

This documentation is intended to be a complete guide to using Figwheel Main. It lives in the Figwheel Main Github repository under the docs/docs directory. If you notice any mistakes or errors please submit a PR.

Conventions

For simplicity this document will use Figwheel and Figwheel Main interchangeably. Both will be referring to the subject of this document: Figwheel Main.