Lifecycle and errors

comins-capture@0.0.1

Await capture and each snapshot output. A document permits one capture at a time; a snapshot permits one output at a time. Concurrency returns BUSY. Cancellation-ignoring work can keep its lease until it actually settles.

import {capture, CaptureError} from 'comins-capture';

async function createPng(target, signal) {
  let snapshot;
  try {
    snapshot = await capture(target, {signal});
    return await snapshot.toBlob({format:'png', signal});
  } catch (error) {
    if (error instanceof CaptureError) console.error(error.code, error.stage);
    throw error;
  } finally {
    snapshot?.dispose();
  }
}

The application connects an AbortController to page/component teardown. Pass its signal through ready/resolver work. Capture and output accept a positive timeoutMs up to 2147483647 ms, default 30000. Use a fresh controller for a new request. Disposal is idempotent, releases owned capture resources, and cancels output; it does not revoke application-created Blob URLs.

Error reference

Code	Check or action
INVALID_TARGET	Connected positive-size HTMLElement in the current document
INVALID_OPTIONS	Supported keys, units, sizes and format-specific options
UNSUPPORTED_ENVIRONMENT	Run capture in a browser after rendering
UNSUPPORTED_CONTENT	Use the supported static input subset
NETWORK_DISABLED	Resolve trusted bytes or explicitly allow their origin
RESOURCE_FAILED	Check loading, decode, CORS/CSP, resolver and signal handling
RESOURCE_UNVERIFIABLE	Make declarations and resource bytes verifiable
SOURCE_CHANGED	Stabilize the target’s DOM, computed styles and geometry
OUTPUT_LIMIT	Reduce requested dimensions or input size
FORMAT_UNSUPPORTED	Select a supported native encoder; no automatic fallback
OUTPUT_MISMATCH	Treat inconsistent size/MIME/decode as a failure
ABORTED	Handle caller cancellation
TIMEOUT	Investigate slow preparation/resources/output before increasing timeout
BUSY	Await the previous operation, including cancellation-ignoring work
DISPOSED	Create a new snapshot
ENGINE_FAILED	Reproduce with a minimal static fixture

CaptureError exposes code and prepare/capture/output stage without retaining source DOM, full resource URLs, or an internal cause. When reporting a problem, include package version/artifact hash, actual browser version, OS, DPR, sanitized fixture/options, expected result, and code/stage. Keep credentials and user data out of reports. See browser support.

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Runnable example · Source guide for this version