This is the reactivity part of SolidJS, extracted out of the UI framework. Check out SolidJS's Reactivity Tutorial to learn how to use this.

This extraction has made changes:

• Anything related to Solid's UI framework has been removed.
• All createX functions, such as createSignal, have been renamed to $x, e.g. $signal.
• $DEVCOMP, $PROXY, and $TRACK have been renamed with their $ replaced with _, e.g. _DEVCOMP.
• The default equalFn has been changed from a === b to (a === 0 && b === 0) || Object.is(a, b), so now NaN will compare as equal to itself.
• Dev exports are always accessible.
• Instead of returning a tuple, $signal returns an object with get and set methods.
• Added readonly function to make object signals read-only.