Fusor is a simple JavaScript library that declaratively manages DOM
Common features
Fusor was inspired by React, and they both share the same ideas:
- Composable functional components
- One-way data flow
- JSX
- DOM updates only if a value or reference changes
- Updates to the parent component will trigger the necessary updates in its children
The main difference
The fundamental difference lies in the separation of concerns within the component lifecycle (aka single-responsibility principle in SOLID)
Fusor | React | |
---|---|---|
Component creation | create() | create_update() |
Component changing | state = x | setState(x) + create_update() |
Component updating | update() | create_update() |
Benefits
Fusor | React | |
---|---|---|
Component data | Created once on initialization | Created on initialization and recreated on every update |
Side effects | Normal JavaScript flow | Complex and verbose hooks mechanics |
Component updates | Explicit, update what and when you need | Implicit, complex |
Component functions | Pure | Context is required |
Library size (gz) | ~2kB | ~44kB |
Code samples
Fusor | React | Comment | |
---|---|---|---|
Create state | let x = 0 |
const [x, setX] = useState(0) |
|
Update state | x = 1 |
setX(1) |
|
Update DOM | update() |
setX(1) |
both are manual calls |
Static prop/child | <p id={x}>{y}</p> |
<p id={x}>{y}</p> |
exactly the same |
Dynamic prop/child | <p id={() => x}>{() => y}</p> |
<p id={x}>{y}</p> |
callbacks used for dynamic values |
Application example
The click$e$update
means:
click
-
e
vent handler -
update
DOM when handler completes -
$
separator symbol - full reference
However
Fusor avoids recreating component data with every update,
preventing a change in the click event handler function reference. This can be important for performance. As a result, useCallback
should be employed in React example to achieve feature parity.
const CountingButton = () => {
const [count, setCount] = useState(0);
const handleClick = useCallback(() => setCount((count) => count + 1), []);
return <button onClick={handleClick}>Clicked {count} times</button>;
};
Verbosity analysis
Verbosity - number of symbols without whitespace
Component | Fusor | React |
---|---|---|
CountingButton | 116 | 189 |
AnalogClock | 776 | 783 |
RequestUsers | 1072 | 1181 |
Other differences
Fusor | React | |
---|---|---|
DOM | Real | Virtual |
Events | Native | Synthetic |
Lifecycle | Native | Complex mechanics |
Attribute names | W3C Specification | Mangled |
Web components support | Complete | Incomplete |
Why Fusor
- It is simple, lightweight, explicit, flexible and compatible
- It extensively utilizes modern JavaScript and browser features
- It follows the principle of doing one thing and doing it well (managing DOM elements)
- It has zero dependencies and is only around 2kB in size
PS
Fusor repo: https://github.com/fusorjs/dom
Thank you!
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