FAQ

Reactivity Chain Propagation

Signals must be passed through $-prefixed variables to maintain reactivity

According to the Signal Compiler compilation strategy, only variables with the $ prefix are recognized by the compiler.

Example with custom hook:

let $msg = ""; // Declaration
const $display = $msg + "hello"; // Derived

const $useText = ($a) => ({
  $text: $a + "hello"
});

// Returns signal
const { $text } = $useText(
  // Input signal
  $display
);

Declaration signal -> Derived signal -> Hook(input signal) -> Hook(return signal) -> Derived signal/destructured signal

Each step compiles the signal, so reactivity is not interrupted. This is the signal reactivity chain propagation.

Why use $ prefix?

First: To mark variables with the $ prefix for compilation into signal-related code. This marker is unambiguous (to avoid conflicts with very few third-party libraries - please use aliases if needed). The compilation plugin is open source - see signal-compiler for details.

Second: To avoid confusion with normal (non-Signal) variables. In large applications, the number of variables is enormous, and developers cannot distinguish between signal variables and normal variables, making debugging difficult.