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Tracing
Inspecting
Tools for seeing what reactivity is doing. Tracing attaches debug metadata to signals, reactions, and dependencies, and getSource prints what triggered the reaction currently running.
Tracing allocates nothing until you turn it on. Leave it off in production and switch it on from the console while debugging.
Tracing allocates nothing until you turn it on. Leave it off in production and switch it on from the console while debugging.
Tracing
Tracing has three levels: off, context, and stack. Context attaches cheap metadata bags so traces can name what changed. Stack adds a captured trace per change and is expensive.
setTracing
setTracing(enabled);Turns context tracing on or off. Disabling it also clears stack capture.
Parameters
| Name | Type | Description |
|---|---|---|
| enabled | boolean | Whether to enable tracing |
setStackCapture
setStackCapture(enabled);Adds stack traces to the tracing context via Error.captureStackTrace. Enabling it implies tracing.
Stack capture runs on every change. Use it to hunt one specific re-run, not as an always-on setting.
Stack capture runs on every change. Use it to hunt one specific re-run, not as an always-on setting.
Parameters
| Name | Type | Description |
|---|---|---|
| enabled | boolean | Whether to capture stack traces |
isTracing
isTracing();Returns
true when tracing is on at either level, context or stack.
isStackCapture
isStackCapture();Returns
true when stack capture is on.
Inspecting
getSource
getSource();Logs the currently running reaction and, when stack capture is on, where it was created or triggered. Call it from inside a reaction during a flush to trace what scheduled it. Outside a flush it reports that no reaction is running.
getSource() writes to the console and returns nothing. Pair it with tracing for named output.
getSource() writes to the console and returns nothing. Pair it with tracing for named output.
Usage
import { reaction, getSource } from '@semantic-ui/reactivity';
reaction(() => { count.get(); getSource(); // logs the reaction and what triggered this run});