Interface Metric

src/types.ts:3–66

import type { ReportOpts } from 'web-vitals';

export interface Metric {
  /**
   * The name of the metric (in acronym form).
   */
  name:
    | 'CLS'
    | 'FCP'
    | 'FID'
    | 'INP'
    | 'LCP'
    | 'TTFB'
    | 'RT'
    | 'TBT'
    | 'NTBT'
    | 'ET'
    | 'INP';
  /**
   * The current value of the metric.
   */
  value: number;
  /**
   * The rating as to whether the metric value is within the "good",
   * "needs improvement", or "poor" thresholds of the metric.
   */
  rating: IVitalsScore;
  /**
   * The delta between the current value and the last-reported value.
   * On the first report, `delta` and `value` will always be the same.
   */
  delta?: number;
  /**
   * A unique ID representing this particular metric instance. This ID can
   * be used by an analytics tool to dedupe multiple values sent for the same
   * metric instance, or to group multiple deltas together and calculate a
   * total. It can also be used to differentiate multiple different metric
   * instances sent from the same page, which can happen if the page is
   * restored from the back/forward cache (in that case new metrics object
   * get created).
   */
  id?: string;
  /**
   * Any performance entries relevant to the metric value calculation.
   * The array may also be empty if the metric value was not based on any
   * entries (e.g. a CLS value of 0 given no layout shifts).
   */
  entries?: PerformanceEntry[];
  /**
   * The type of navigation
   *
   * Navigation Timing API (or `undefined` if the browser doesn't
   * support that API). For pages that are restored from the bfcache, this
   * value will be 'back-forward-cache'.
   */
  navigationType?: INavigationType;

  /**
   * An object containing potentially-helpful debugging information that
   * can be sent along with the metric value for the current page visit in