{"version":3,"file":"getLCP.js","sources":["../../../../src/metrics/web-vitals/getLCP.ts"],"sourcesContent":["/*\n * Copyright 2020 Google LLC\n *\n * Licensed under the Apache License, Version 2.0 (the \"License\");\n * you may not use this file except in compliance with the License.\n * You may obtain a copy of the License at\n *\n *     https://www.apache.org/licenses/LICENSE-2.0\n *\n * Unless required by applicable law or agreed to in writing, software\n * distributed under the License is distributed on an \"AS IS\" BASIS,\n * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n * See the License for the specific language governing permissions and\n * limitations under the License.\n */\n\nimport { bindReporter } from './lib/bindReporter';\nimport { getActivationStart } from './lib/getActivationStart';\nimport { getVisibilityWatcher } from './lib/getVisibilityWatcher';\nimport { addPageListener, removePageListener } from './lib/globalListeners';\nimport { initMetric } from './lib/initMetric';\nimport { initUnique } from './lib/initUnique';\nimport { LCPEntryManager } from './lib/LCPEntryManager';\nimport { observe } from './lib/observe';\nimport { runOnce } from './lib/runOnce';\nimport { whenActivated } from './lib/whenActivated';\nimport { whenIdleOrHidden } from './lib/whenIdleOrHidden';\nimport type { LCPMetric, MetricRatingThresholds, ReportOpts } from './types';\n\n/** Thresholds for LCP. See https://web.dev/articles/lcp#what_is_a_good_lcp_score */\nexport const LCPThresholds: MetricRatingThresholds = [2500, 4000];\n\n/**\n * Calculates the [LCP](https://web.dev/articles/lcp) value for the current page and\n * calls the `callback` function once the value is ready (along with the\n * relevant `largest-contentful-paint` performance entry used to determine the\n * value). The reported value is a `DOMHighResTimeStamp`.\n *\n * If the `reportAllChanges` configuration option is set to `true`, the\n * `callback` function will be called any time a new `largest-contentful-paint`\n * performance entry is dispatched, or once the final value of the metric has\n * been determined.\n */\nexport const onLCP = (onReport: (metric: LCPMetric) => void, opts: ReportOpts = {}) => {\n  whenActivated(() => {\n    const visibilityWatcher = getVisibilityWatcher();\n    const metric = initMetric('LCP');\n    let report: ReturnType<typeof bindReporter>;\n\n    const lcpEntryManager = initUnique(opts, LCPEntryManager);\n\n    const handleEntries = (entries: LCPMetric['entries']) => {\n      // If reportAllChanges is set then call this function for each entry,\n      // otherwise only consider the last one.\n      if (!opts.reportAllChanges) {\n        // eslint-disable-next-line no-param-reassign\n        entries = entries.slice(-1);\n      }\n\n      for (const entry of entries) {\n        lcpEntryManager._processEntry(entry);\n\n        // Only report if the page wasn't hidden prior to LCP.\n        if (entry.startTime < visibilityWatcher.firstHiddenTime) {\n          // The startTime attribute returns the value of the renderTime if it is\n          // not 0, and the value of the loadTime otherwise. The activationStart\n          // reference is used because LCP should be relative to page activation\n          // rather than navigation start if the page was prerendered. But in cases\n          // where `activationStart` occurs after the LCP, this time should be\n          // clamped at 0.\n          metric.value = Math.max(entry.startTime - getActivationStart(), 0);\n          metric.entries = [entry];\n          report();\n        }\n      }\n    };\n\n    const po = observe('largest-contentful-paint', handleEntries);\n\n    if (po) {\n      report = bindReporter(onReport, metric, LCPThresholds, opts.reportAllChanges);\n\n      // Ensure this logic only runs once, since it can be triggered from\n      // any of three different event listeners below.\n      const stopListening = runOnce(() => {\n        handleEntries(po.takeRecords() as LCPMetric['entries']);\n        po.disconnect();\n        report(true);\n      });\n\n      // Need a separate wrapper to ensure the `runOnce` function above is\n      // common for all three functions\n      const stopListeningWrapper = (event: Event) => {\n        if (event.isTrusted) {\n          // Wrap the listener in an idle callback so it's run in a separate\n          // task to reduce potential INP impact.\n          // https://github.com/GoogleChrome/web-vitals/issues/383\n          whenIdleOrHidden(stopListening);\n          removePageListener(event.type, stopListeningWrapper, {\n            capture: true,\n          });\n        }\n      };\n\n      // Stop listening after input or visibilitychange.\n      // Note: while scrolling is an input that stops LCP observation, it's\n      // unreliable since it can be programmatically generated.\n      // See: https://github.com/GoogleChrome/web-vitals/issues/75\n      for (const type of ['keydown', 'click', 'visibilitychange']) {\n        addPageListener(type, stopListeningWrapper, {\n          capture: true,\n        });\n      }\n    }\n  });\n};\n"],"names":[],"mappings":";;;;;;;;;;;;AA8BO,MAAM,aAAA,GAAwC,CAAC,IAAA,EAAM,GAAI;AAazD,MAAM,KAAA,GAAQ,CAAC,QAAA,EAAuC,IAAA,GAAmB,EAAC,KAAM;AACrF,EAAA,aAAA,CAAc,MAAM;AAClB,IAAA,MAAM,oBAAoB,oBAAA,EAAqB;AAC/C,IAAA,MAAM,MAAA,GAAS,WAAW,KAAK,CAAA;AAC/B,IAAA,IAAI,MAAA;AAEJ,IAAA,MAAM,eAAA,GAAkB,UAAA,CAAW,IAAA,EAAM,eAAe,CAAA;AAExD,IAAA,MAAM,aAAA,GAAgB,CAAC,OAAA,KAAkC;AAGvD,MAAA,IAAI,CAAC,KAAK,gBAAA,EAAkB;AAE1B,QAAA,OAAA,GAAU,OAAA,CAAQ,MAAM,EAAE,CAAA;AAAA,MAC5B;AAEA,MAAA,KAAA,MAAW,SAAS,OAAA,EAAS;AAC3B,QAAA,eAAA,CAAgB,cAAc,KAAK,CAAA;AAGnC,QAAA,IAAI,KAAA,CAAM,SAAA,GAAY,iBAAA,CAAkB,eAAA,EAAiB;AAOvD,UAAA,MAAA,CAAO,QAAQ,IAAA,CAAK,GAAA,CAAI,MAAM,SAAA,GAAY,kBAAA,IAAsB,CAAC,CAAA;AACjE,UAAA,MAAA,CAAO,OAAA,GAAU,CAAC,KAAK,CAAA;AACvB,UAAA,MAAA,EAAO;AAAA,QACT;AAAA,MACF;AAAA,IACF,CAAA;AAEA,IAAA,MAAM,EAAA,GAAK,OAAA,CAAQ,0BAAA,EAA4B,aAAa,CAAA;AAE5D,IAAA,IAAI,EAAA,EAAI;AACN,MAAA,MAAA,GAAS,YAAA,CAAa,QAAA,EAAU,MAAA,EAAQ,aAAA,EAAe,KAAK,gBAAgB,CAAA;AAI5E,MAAA,MAAM,aAAA,GAAgB,QAAQ,MAAM;AAClC,QAAA,aAAA,CAAc,EAAA,CAAG,aAAqC,CAAA;AACtD,QAAA,EAAA,CAAG,UAAA,EAAW;AACd,QAAA,MAAA,CAAO,IAAI,CAAA;AAAA,MACb,CAAC,CAAA;AAID,MAAA,MAAM,oBAAA,GAAuB,CAAC,KAAA,KAAiB;AAC7C,QAAA,IAAI,MAAM,SAAA,EAAW;AAInB,UAAA,gBAAA,CAAiB,aAAa,CAAA;AAC9B,UAAA,kBAAA,CAAmB,KAAA,CAAM,MAAM,oBAAA,EAAsB;AAAA,YACnD,OAAA,EAAS;AAAA,WACV,CAAA;AAAA,QACH;AAAA,MACF,CAAA;AAMA,MAAA,KAAA,MAAW,IAAA,IAAQ,CAAC,SAAA,EAAW,OAAA,EAAS,kBAAkB,CAAA,EAAG;AAC3D,QAAA,eAAA,CAAgB,MAAM,oBAAA,EAAsB;AAAA,UAC1C,OAAA,EAAS;AAAA,SACV,CAAA;AAAA,MACH;AAAA,IACF;AAAA,EACF,CAAC,CAAA;AACH;;;;"}