@sv-use/core/dist/observe-performance/index.svelte.d.ts

A collection of Svelte 5 utilities.

import { type ConfigurableWindow } from '../__internal__/configurable.js';
import type { CleanupFunction } from '../__internal__/types.js';
export declare const performanceEntryTypes: readonly ["element", "event", "first-input", "largest-contentful-paint", "layout-shift", "long-animation-frame", "longtask", "mark", "measure", "navigation", "paint", "resource", "taskattribution", "visibility-state"];
export type PerformanceEntryType = (typeof performanceEntryTypes)[number];
interface ObservePerformanceOptions extends ConfigurableWindow {
    /**
     * Whether to start the observer immediately or not.
     * @default true
     */
    immediate?: boolean;
    /**
     * A single string specifying exactly one performance entry type to observe.
     *
     * May not be used together with the {@link entryTypes} option.
     */
    type?: PerformanceEntryType;
    /**
     * A boolean flag to indicate whether buffered entries should be queued into the observer's buffer.
     *
     * Must be used only with the {@link type} option.
     * @default false
     */
    buffered?: boolean;
    /**
     * A {@link DOMHighResTimeStamp} defining the threshold for {@link https://developer.mozilla.org/en-US/docs/Web/API/PerformanceEventTiming | PerformanceEventTiming} entries.
     *
     * Defaults to 104ms and is rounded to the nearest of 8ms. Lowest possible threshold is 16ms.
     *
     * May not be used together with the {@link entryTypes} option.
     */
    durationThreshold?: DOMHighResTimeStamp;
    /**
     * An array of strings, each specifying one performance entry type to observe.
     *
     * Unrecognized types are ignored, though the browser may output a warning message to the console to help developers debug their code. If no valid types are found, observe() has no effect.
     */
    entryTypes?: PerformanceEntryType[];
}
interface ObservePerformanceReturn {
    /** Whether the {@link https://developer.mozilla.org/en-US/docs/Web/API/PerformanceObserver `Performance Observer API`} is supported or not. */
    readonly isSupported: boolean;
    /**
     * Resumes the performance observer.
     *
     * Is called automatically if `options.immediate` is set to `true`.
     */
    resume: () => void;
    /**
     * Pauses the observer.
     *
     * Can be restarted with {@link resume | `resume`}.
     */
    pause: () => void;
    /** Cleans up the observer. */
    cleanup: CleanupFunction;
}
/**
 * Observes performance metrics.
 * @param callback The callback for when performance entry events are recorded.
 * @param options Additional options to customize the behavior.
 * @see https://svelte-librarian.github.io/sv-use/docs/core/observe-performance
 */
export declare function observePerformance(callback: PerformanceObserverCallback, options: ObservePerformanceOptions): ObservePerformanceReturn;
export {};