# Write a custom jComponent > Register a reusable component with COMPONENT(), render it in make(), react to state changes in setter() and write back with set(). Framework: jcomponent20 Product: jComponent 20 (jcomponent@20) Language: en Content-SHA256: e7cce28ba59dc0aeba03d3e4d38b42f387d4ab3717e831f55440d79e4914233b Snapshot: c0700e321579725c5cf4f5ace1ad7d2866d1b4f93c24a63c0b41b6b7998e976c Sources: jcomponent20@3fedd009a277f50fddc608b97afbec553b67c51b Review: not-recorded A component is declared with `COMPONENT(name, config, declaration)`. The second argument is the default configuration as a string (`key:value;key:value`). The declaration receives `self` (the component instance) and `config` (the parsed configuration). - `self.make` runs once, when the component is created. Build the DOM here. - `self.setter(value)` runs every time the value of the component's `path` changes. - `self.set(value)` writes a new value to the `path`; `self.get()` reads it. Use the component with a `` element. `name` selects the declaration, `path` the state and `config` overrides the defaults. ```html public/index.html jComponent

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``` The `ui-bind` next to the component shows that both read the same state: clicking the button changes the path and every element bound to it updates.