/**
* @license
* Copyright 2016 Google Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict';
const Audit = require('../audit');
const Formatter = require('../../../formatters/formatter');
class CriticalRequestChains extends Audit {
/**
* @override
*/
static get meta() {
return {
category: 'Performance',
name: 'critical-request-chains',
description: 'Critical Request Chains',
optimalValue: 0,
requiredArtifacts: ['criticalRequestChains']
};
}
/**
* Audits the page to give a score for First Meaningful Paint.
* @param {!Artifacts} artifacts The artifacts from the gather phase.
* @return {!AuditResult} The score from the audit, ranging from 0-100.
*/
static audit(artifacts) {
let chainCount = 0;
function walk(node, depth) {
const children = Object.keys(node);
// Since a leaf node indicates the end of a chain, we can inspect the number
// of child nodes, and, if the count is zero, increment the count.
if (children.length === 0) {
chainCount++;
}
children.forEach(id => {
const child = node[id];
walk(child.children, depth + 1);
}, '');
}
walk(artifacts.criticalRequestChains, 0);
return CriticalRequestChains.generateAuditResult({
value: chainCount,
optimalValue: this.meta.optimalValue,
extendedInfo: {
formatter: Formatter.SUPPORTED_FORMATS.CRITICAL_REQUEST_CHAINS,
value: artifacts.criticalRequestChains
}
});
}
}
module.exports = CriticalRequestChains;
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