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Marko vs React: An In-depth Look

by Patrick Steele-IdemMarch 21st, 2017

Too Long; Didn't Read

In this article we will take an in-depth look at the differences and similarities between <a href="http://markojs.com/" target="_blank">Marko</a> and <a href="https://hackernoon.com/tagged/react" target="_blank">React</a> from the perspective of the maintainers of Marko.

Companies Mentioned

featured image - Marko vs React: An In-depth Look

In this article we will take an in-depth look at the differences and similarities between Marko and React from the perspective of the maintainers of Marko.

Example • Similarities • Differences Syntax • Components • API • Custom tags Async • Compiler • Tools • Why Marko?

On the surface, Marko and React have a lot in common and both are trying to solve very similar problems. Specifically, both Marko and React allow developers to build web applications based on UI components and both free developers from having to write code to manually update the DOM. While many of the features in Marko were inspired by React, Marko and React offer very different usability and performance characteristics. Marko was designed to avoid almost all boilerplate and is more closely aligned with HTML. In almost all cases, a Marko UI component will require less lines of code than its React JSX equivalent while maintaining readability and allowing the same expressiveness as JSX. In addition, Marko is highly optimized for use on the server and in the browser and has a much smaller weight:

Because the Marko JavaScript library is much smaller than React, it will require less time to load and parse and this will drastically improve page load times on slow connections or on older devices. Based on our benchmarks, Marko consistently outperforms React by a significant margin on both the server and in the browser.

Example

The following code highlights some of the differences between Marko and React JSX using a somewhat contrived UI component as an example:

React JSX

Marko

Similarities

Marko and React have the following in common:

UI component-based
JavaScript and HTML markup can be intertwined
No restrictions on JavaScript (use ES5 or ES2015+, your choice)
Virtual DOM rendering in the browser
DOM diffing/patching is used to reconcile views
Both support keyed element matching
UI components can have input properties
UI components can have internal state
Changes to state trigger an asynchronous update to the DOM
Updates to the DOM are batched
Compatible with central application state stores such as Redux and MobX
UI components can be embedded using custom tags
Declarative event binding (no domEl.addEventListener() needed)
Support for all DOM events
Event delegation utilized internally for DOM events that bubble
IE9+ support
Similar lifecycle events for UI components
JSX and Marko both compile to JavaScript

Differences

At a high level here are some differences:

Differences in rendering

Improved performance: Marko renders to a virtual DOM in the browser and directly to an HTML stream on the server (Marko supports multiple compilation targets).
Improved performance: Marko supports asynchronous rendering with early flushing of HTML for improvements in actual and perceived page load times.
Improved performance: React requires an additional client-side re-render if a page is initially rendered on the server while Marko does not.
Improved ease of use: Marko automatically serializes UI component state and input down to the browser so that the browser can pick up right where the server left off.
Improved ease of use: Marko is suitable for rendering an entire HTML page on the server with support for tags such as <doctype> and <html>.

Differences in syntax

Improved ease of use: Marko uses the HTML-JS syntax and the JSX syntax is offered for React.
Improved ease of use: Marko supports both a concise syntax and a familiar HTML syntax.
Improved ease of use: JSX requires strict XML while Marko aligns with less strict HTML that web developers are used to.
Improved ease of use: With Marko, all HTML attribute values are parsed as JavaScript expressions.
Improved ease of use: Marko supports simple directives for conditionals, looping, etc.
JSX limitation: JSX is “just JavaScript” but requires expressions that preclude the usage of JavaScript statements such as if/else/for in certain places.

Differences in compilation

Improved performance: Marko supports multiple compilation outputs (Marko VDOM and HTML streaming are currently supported).
Improved ease of use: Marko compiles UI components to JavaScript modules that export a rendering API.
Expanded capabilities: Marko supports a robust API for controlling how custom tags and custom attributes get compiled and it supports compile-time transforms based on a friendly Abstract Syntax Tree (AST).
Improved performance: JSX is just syntactic sugar that translates elements to createElement() function calls while the Marko compiler has full control over how things are compiled and optimized.
Improved ease of use: React requires all UI components to be explicitly imported before they can be used as custom tags while Marko supports both explicit importing and implicit importing.
Improved performance: Marko has a modular runtime and the compiler generates code that only imports the parts of the Marko runtime that are needed for much smaller builds.
Improved ease of use: Marko supports optional compile-time checks to ensure that only allowed attributes are passed to custom tags. (React PropTypes only provide validation at render-time)
Improved ease of use: Marko validates all tag names at compile-time.
Improved ease of use: Marko provides its own compiler that integrates with Node.js and JavaScript module bundlers while React JSX requires babel and custom babel transforms.

Differences in UI components

Reduced boilerplate: No explicit extending of JavaScript classes in Marko (in contrast to class Counter extends React.Component in React).
Improved ease of use: Modifications to UI component state are synchronous with Marko while the rules for React are more complicated.
Improved ease of use: Marko watches UI component state objects to allow state to be modified directly (e.g., this.state.count++).
Improved ease of use: Marko supports single-file UI components combining JavaScript behavior, CSS styling (with support for CSS preprocessors) and HTML markup. (React requires using one of the many CSS in JS solutions if you want styles in the same file as your component and there is no standard in the community)
Improved maintainability: Marko supports a seamless transition from a single-file UI component to a multi-file UI component.
Improved performance: Marko assumes UI components are pure by default and skips re-rendering when input properties and state are unchanged (React requires extending React.PureComponent).

Differences in event systems

Reduced complexity: React utilizes synthetic events while Marko utilizes real DOM events.
Improved ease of use: Custom events are emitted using the EventEmitter API in Marko (e.g., this.emit('myCustomEvent', arg1, arg2)).
Improved ease of use: Marko has a consistent approach for listening to both native DOM events and custom events.
Improved ease of use: React requires passing aroundFunction references for custom events while Marko automatically delegates emitted custom events to event handler methods on components.
Improved ease of use: Marko provides a simple mechanism for binding additional arguments to event handler methods and this will be the component instance.

Differences in compatibility

Marko limitation: Marko has no support for native mobile similar to React Native (although with Marko VDOM rendering, this is possible).
Marko limitation: Marko requires a JavaScript module bundler (such as Lasso, Webpack, Rollup or Browserify) to be used in the browser since Marko UI components compile down to JavaScript modules. (we consider using a JavaScript module bundler a best practice)

In the sections below we will take a closer look at some of the differences between Marko and React.

Syntax

Both Marko and React JSX allow HTML markup and JavaScript to be combined into a single file and both support building web applications based on UI components. Marko utilizes an HTML-JS syntax while most React apps use the JSX syntax.

React JSX makes JavaScript more like HTML and Marko makes HTML more like JavaScript.

In the end, both Marko and React allow JavaScript and HTML to be intertwined.

Syntax: attributes

React JSX

In React JSX, all attribute values are parsed as string values unless {} is used.

Marko

With Marko, all attribute values are parsed as JavaScript expressions. The following Marko code is equivalent to the React JSX code above:

Syntax: inline JavaScript

React JSX

React JSX starts with JavaScript and allows XML elements to be inlined as shown below:

Marko

Marko starts out in HTML, but it allows JavaScript to be inlined in a clean and maintainable way. Unlike other template languages, Marko aims to allow the full power of JavaScript. The following Marko code is equivalent to the React JSX code above:

Lines prefixed with $ are directly added to the compiled JavaScript output inside the compiled render() function (for JavaScript code that should run for every render). Lines prefixed with static are directly added to the compiled JavaScript output outside the render() function (for code that should only run once when the template is loaded).

Syntax: HTML support

With Marko any valid HTML markup can be used inside a Marko template. This is not the case with React. The following quote is from the React documentation:

Caveat:

Since JSX is closer to JavaScript than HTML, React DOM uses camelCase property naming convention instead of HTML attribute names.

For example, class becomes [className](https://developer.mozilla.org/en-US/docs/Web/API/Element/className) in JSX, and tabindex becomes [tabIndex](https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/tabIndex).

As a result of this caveat for React, tools for converting HTML to JSX exist.

React JSX

Marko

Syntax: conditionals

JSX is syntactic sugar on top of JavaScript, but it requires expressions, so simple things like an if/else/for statement don’t work on their own within a JSX element. As a result, you must either use a ternary expression, an immediately invoked function expression, function call expression, or the experimental do {} expression (stage 0 at the time of writing). This is not an issue for Marko, and directives such as if() and for() can be used anywhere as shown below:

React JSX

Marko

Marko also allows directives to be used as attributes for a more condensed template:

Syntax: looping

React JSX

Marko

Syntax: HTML shorthand

Marko supports a shorthand based on CSS selectors for less code.

React does not support these helpful shorthands.

Syntax: concise

Marko supports a concise syntax that drops angled brackets and ending tags in favor of indentation. Here’s how the Marko syntax options compare:

Marko HTML syntax

Marko concise syntax

Marko mixed syntax

The HTML syntax and the concise syntax can be used together:

React JSX

React does not offer a concise syntax.

Components

Marko starts with simple HTML and allows UI component logic to easily be layered on top.

React JSX

A React UI component is typically implemented as a class that extends React.Component:

React also supports a more concise functional component:

However, if state or lifecycle events are needed then a functional UI component must be converted to a class component:

Marko

Here is the same component in Marko:

Behavior can easily be added to any Marko UI component:

Marko also allows JavaScript behavior, CSS styling and HTML markup to be embedded in the Marko template as a single file UI component:

API

Marko compiles component to JavaScript modules that export an API for rendering the component as shown below:

The same UI component can be rendered to a stream such as a writable HTTP response stream:

The user’s of a Marko UI component do not need to know that the component was implemented using Marko.

Contrast this with React as an example:

On top of that, React requires that a different module be imported to render the exact same UI component on the server:

Custom tags

React JSX

With React, all custom tags for UI components must be explicitly imported:

Marko

Marko supports a mechanism for automatically discovering custom tags for UI components based on the project directory structure. Marko walks up the directory tree to discover all components/ directories and it will also automatically discover custom tags exported by installed packages. This approach negates the need for explicitly importing a custom tag to reduce the amount of code needed in a Marko template. For example given the following directory structure:

.├── components/│ ├── hello.marko│ └── good-bye.marko└── index.marko

The <hello> tag and the <good-bye> tag nested below the components/ directory will automatically be made available to the index.marko at the root:

This approach also allows editors and IDEs to offer autocompletion for custom tags.

Async

Even after rendering has started, Marko allows parts of the view to be rendered asynchronously using the [<await>](http://markojs.com/docs/core-tags/#codeampltawaitgtcode) tag as shown in the following Marko template:

Compiler

Marko compiles a template differently based on whether or not it will be used on the server or in the browser. For example, given the following template:

Compiled for the server:

Compiled for the browser:

Compile-time code transforms

The Marko compiler was built to support compile-time code generators for custom tags and it also provides support for compile-time transforms. While Babel allows code transformations of JavaScript, the Marko compiler provides support for resolving custom tags declaratively and the Marko AST provides for very powerful and simple transformations as shown in the following code for rendering Markdown to HTML at compile-time:

components/markdown/code-generator.js:

The <markdown> tag can then be used as shown below:

In this example, after the template is compiled, the marked library is no longer needed at render-time.

Tools

Marko and React offer a variety of developer tools. The Marko developer tools are constantly evolving, but Marko currently provides tools for unit testing UI components, precompiling .marko files and generating configuration-less apps (similar to create-react-app). Currently, there are no Marko developer tools that integrate with the browser, but this is something we would like to see in the future. We will go into more detail on the Marko developer tools in a future post.

IDE and editor support

Marko offers syntax highlighting across all major IDEs and editors, as well as on GitHub. Marko provides first-class support for the Atom editor with syntax highlighting, Autocomplete for both HTML and custom tags, Hyperclick to quickly jump to referenced files and methods, and Pretty printing to keep your code readable.

Why Marko?

Here are just a few reasons you should consider using Marko over React:

Marko requires much less boilerplate.
Marko has much better performance based on our benchmarks.
Marko offers a clean and powerful syntax that aligns with HTML while also allowing the full power of JavaScript.
Marko has much less complexity and a very small runtime.
Marko has a much lower page weight for faster page loads.
Marko has strong integrations with Node.js.
Marko allows for extremely powerful IDE and editor plugins (see the Marko plugin for Atom as an example).
Marko has a powerful compiler that allows new features to be added without introducing bloat.
eBay relies heavily on Marko and it is being used to build ebay.com (including the mobile web).
Marko has a strong and growing community on GitHub and in Gitter.

Interested in learning more about Marko? If so, you can get additional information on the Marko website. Join the conversation and contribute on GitHub and follow us on Twitter.

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