| 1 | import { CLSMetric, MetricRatingThresholds, ReportOpts } from './types.js';
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| 2 | /** Thresholds for CLS. See https://web.dev/articles/cls#what_is_a_good_cls_score */
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| 3 | export declare const CLSThresholds: MetricRatingThresholds;
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| 4 | /**
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| 5 | * Calculates the [CLS](https://web.dev/articles/cls) value for the current page and
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| 6 | * calls the `callback` function once the value is ready to be reported, along
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| 7 | * with all `layout-shift` performance entries that were used in the metric
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| 8 | * value calculation. The reported value is a `double` (corresponding to a
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| 9 | * [layout shift score](https://web.dev/articles/cls#layout_shift_score)).
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| 10 | *
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| 11 | * If the `reportAllChanges` configuration option is set to `true`, the
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| 12 | * `callback` function will be called as soon as the value is initially
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| 13 | * determined as well as any time the value changes throughout the page
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| 14 | * lifespan.
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| 15 | *
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| 16 | * _**Important:** CLS should be continually monitored for changes throughout
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| 17 | * the entire lifespan of a page—including if the user returns to the page after
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| 18 | * it's been hidden/backgrounded. However, since browsers often [will not fire
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| 19 | * additional callbacks once the user has backgrounded a
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| 20 | * page](https://developer.chrome.com/blog/page-lifecycle-api/#advice-hidden),
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| 21 | * `callback` is always called when the page's visibility state changes to
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| 22 | * hidden. As a result, the `callback` function might be called multiple times
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| 23 | * during the same page load._
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| 24 | */
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| 25 | export declare const onCLS: (onReport: (metric: CLSMetric) => void, opts?: ReportOpts) => void;
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