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seperate the AxeObserver and log function
# Conflicts: # README.MD
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Juliette Pretot
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Nov 21, 2019
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,111 @@ | ||
| import axeCore from 'axe-core' | ||
|
|
||
| // If requestIdleCallback is not supported, we fallback to setTimeout | ||
| // Ref: https://developers.google.com/web/updates/2015/08/using-requestidlecallback | ||
| const requestIdleCallback = | ||
| window.requestIdleCallback || | ||
| function(callback) { | ||
| setTimeout(callback, 1) | ||
| } | ||
|
|
||
| // Define own debounce function to avoid excess dependencies | ||
| // Ref: https://chrisboakes.com/how-a-javascript-debounce-function-works/ | ||
| function debounce(callback, wait) { | ||
| let timeout | ||
| return (...args) => { | ||
| clearTimeout(timeout) | ||
| timeout = setTimeout(() => callback.apply(this, args), wait) | ||
| } | ||
| } | ||
|
|
||
| // The AxeObserver class takes a violationsCallback, which is invoked with an | ||
| // array of observed violations. | ||
| export default class AxeObserver { | ||
| constructor( | ||
| violationsCallback, | ||
| axeConfiguration = { | ||
| reporter: 'v2', | ||
| checks: [ | ||
| { | ||
| id: 'color-contrast', | ||
| options: { | ||
| // Prevent axe from automatically scrolling | ||
| noScroll: true | ||
| } | ||
| } | ||
| ] | ||
| } | ||
| ) { | ||
| if (typeof violationsCallback !== 'function') { | ||
| throw new Error( | ||
| 'The AxeObserver constructor requires a violationsCallback' | ||
| ) | ||
| } | ||
|
|
||
| this._violationsCallback = violationsCallback | ||
|
|
||
| this.observe = this.observe.bind(this) | ||
| this.disconnect = this.disconnect.bind(this) | ||
| this._auditTargetNode = this._auditTargetNode.bind(this) | ||
|
|
||
| this._mutationObservers = [] | ||
| this._alreadyReportedIncidents = new Set() | ||
|
|
||
| axeCore.configure(axeConfiguration) | ||
| } | ||
| observe(targetNode, debounceMs = 1000) { | ||
| if (!targetNode) { | ||
| throw new Error('AxeObserver.observe requires a targetNode') | ||
| } | ||
|
|
||
| const scheduleAudit = debounce( | ||
| () => requestIdleCallback(() => this._auditTargetNode(targetNode)), | ||
| debounceMs | ||
| ) | ||
| const mutationObserver = new window.MutationObserver(scheduleAudit) | ||
|
|
||
| // observe changes | ||
| mutationObserver.observe(targetNode, { | ||
| attributes: true, | ||
| subtree: true | ||
| }) | ||
|
|
||
| this._mutationObservers.push(mutationObserver) | ||
|
|
||
| // run initial audit | ||
| scheduleAudit(targetNode) | ||
| } | ||
| disconnect() { | ||
| this._mutationObservers.forEach(mutationObserver => { | ||
| mutationObserver.disconnect() | ||
| }) | ||
| } | ||
| async _auditTargetNode(targetNode) { | ||
| const response = await axeCore.run(targetNode) | ||
|
|
||
| const violationsToReport = response.violations.filter(violation => { | ||
| const filteredNodes = violation.nodes.filter(node => { | ||
| const key = node.target.toString() + violation.id | ||
|
|
||
| const wasAlreadyReported = this._alreadyReportedIncidents.has(key) | ||
|
|
||
| if (wasAlreadyReported) { | ||
| // filter out this violation for this node | ||
| return false | ||
| } else { | ||
| // add to alreadyReportedIncidents as we'll report it now | ||
| this._alreadyReportedIncidents.add(key) | ||
| return true | ||
| } | ||
| }) | ||
|
|
||
| return filteredNodes.length > 0 | ||
| }) | ||
|
|
||
| const hasViolationsToReport = violationsToReport.length > 0 | ||
|
|
||
| if (hasViolationsToReport) { | ||
| this._violationsCallback(violationsToReport) | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,182 +1,4 @@ | ||
| import axe from 'axe-core' | ||
| import AxeObserver from './AxeObserver.js' | ||
| import logViolations from './logViolations.js' | ||
|
|
||
| // If requestIdleCallback is not supported, we fallback to setTimeout | ||
| // Ref: https://developers.google.com/web/updates/2015/08/using-requestidlecallback | ||
| const requestIdleCallback = | ||
| window.requestIdleCallback || | ||
| function(callback) { | ||
| setTimeout(callback, 1) | ||
| } | ||
|
|
||
| // Define own debounce function to avoid excess dependencies | ||
| // Ref: https://chrisboakes.com/how-a-javascript-debounce-function-works/ | ||
| function debounce(callback, wait) { | ||
| let timeout | ||
| return (...args) => { | ||
| clearTimeout(timeout) | ||
| timeout = setTimeout(() => callback.apply(this, args), wait) | ||
| } | ||
| } | ||
|
|
||
| class AxeReporter { | ||
| constructor( | ||
| axeConfiguration = { | ||
| reporter: 'v2', | ||
| checks: [ | ||
| { | ||
| id: 'color-contrast', | ||
| options: { | ||
| // Prevent axe from automatically scrolling | ||
| noScroll: true | ||
| } | ||
| } | ||
| ] | ||
| } | ||
| ) { | ||
| this.observe = this.observe.bind(this) | ||
| this.disconnect = this.disconnect.bind(this) | ||
| this._auditTargetNode = this._auditTargetNode.bind(this) | ||
|
|
||
| this._mutationObservers = [] | ||
| this._alreadyReportedIncidents = new Set() | ||
|
|
||
| axe.configure(axeConfiguration) | ||
| } | ||
| observe(targetNode, debounceMs = 1000) { | ||
| if (!targetNode) { | ||
| throw new Error('AxeReporter.observe requires a targetNode') | ||
| } | ||
|
|
||
| const scheduleAudit = debounce( | ||
| () => requestIdleCallback(() => this._auditTargetNode(targetNode)), | ||
| debounceMs | ||
| ) | ||
| const mutationObserver = new window.MutationObserver(scheduleAudit) | ||
|
|
||
| // observe changes | ||
| mutationObserver.observe(targetNode, { | ||
| attributes: true, | ||
| subtree: true | ||
| }) | ||
|
|
||
| this._mutationObservers.push(mutationObserver) | ||
|
|
||
| // run initial audit | ||
| scheduleAudit(targetNode) | ||
| } | ||
| disconnect() { | ||
| this._mutationObservers.forEach(mutationObserver => { | ||
| mutationObserver.disconnect() | ||
| }) | ||
| } | ||
| async _auditTargetNode(targetNode) { | ||
| const response = await axe.run(targetNode) | ||
|
|
||
| const violationsToReport = response.violations.filter(violation => { | ||
| const filteredNodes = violation.nodes.filter(node => { | ||
| const key = node.target.toString() + violation.id | ||
|
|
||
| const wasAlreadyReported = this._alreadyReportedIncidents.has(key) | ||
|
|
||
| if (wasAlreadyReported) { | ||
| // filter out this violation for this node | ||
| return false | ||
| } else { | ||
| // add to alreadyReportedIncidents as we'll report it now | ||
| this._alreadyReportedIncidents.add(key) | ||
| return true | ||
| } | ||
| }) | ||
|
|
||
| return filteredNodes.length > 0 | ||
| }) | ||
|
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| const hasViolationsToReport = violationsToReport.length > 0 | ||
|
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| if (hasViolationsToReport) { | ||
| AxeReporter.reportViolations(violationsToReport) | ||
| } | ||
| } | ||
| static REPORT_STYLES = { | ||
| critical: 'color:red; font-weight:bold;', | ||
| serious: 'color:red; font-weight:normal;', | ||
| moderate: 'color:orange; font-weight:bold;', | ||
| minor: 'color:orange; font-weight:normal;', | ||
| elementLog: 'font-weight:bold; font-family:Courier;', | ||
| defaultReset: 'font-color:black; font-weight:normal;' | ||
| } | ||
| static reportViolations(violations) { | ||
| console.group('%cNew aXe issues', AxeReporter.REPORT_STYLES.serious) | ||
| violations.forEach(violation => { | ||
| const format = | ||
| AxeReporter.REPORT_STYLES[violation.impact] || | ||
| AxeReporter.REPORT_STYLES.minor | ||
| console.groupCollapsed( | ||
| '%c%s: %c%s %s', | ||
| format, | ||
| violation.impact, | ||
| AxeReporter.REPORT_STYLES.defaultReset, | ||
| violation.help, | ||
| violation.helpUrl | ||
| ) | ||
| console.groupEnd() | ||
| violation.nodes.forEach(node => { | ||
| AxeReporter.reportFailureSummary(node, 'any') | ||
| AxeReporter.reportFailureSummary(node, 'none') | ||
| }) | ||
| }) | ||
| console.groupEnd() | ||
| } | ||
| static reportFailureSummary(node, key) { | ||
| // This method based off react-axe's failureSummary | ||
| // Ref: https://github.com/dequelabs/react-axe | ||
| function logElement(node, logFn) { | ||
| const elementInDocument = document.querySelector(node.target.toString()) | ||
| if (!elementInDocument) { | ||
| logFn( | ||
| 'Selector: %c%s', | ||
| AxeReporter.REPORT_STYLES.elementLog, | ||
| node.target.toString() | ||
| ) | ||
| } else { | ||
| logFn('Element: %o', elementInDocument) | ||
| } | ||
| } | ||
|
|
||
| function logHtml(node) { | ||
| console.log('HTML: %c%s', AxeReporter.REPORT_STYLES.elementLog, node.html) | ||
| } | ||
|
|
||
| function logFailureMessage(node, key) { | ||
| const message = axe._audit.data.failureSummaries[key].failureMessage( | ||
| node[key].map(check => check.message || '') | ||
| ) | ||
|
|
||
| console.error(message) | ||
| } | ||
|
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| if (node[key].length > 0) { | ||
| logElement(node, console.groupCollapsed) | ||
| logHtml(node) | ||
| logFailureMessage(node, key) | ||
|
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| const relatedNodes = node[key].reduce( | ||
| (accumulator, check) => [...accumulator, ...check.relatedNodes], | ||
| [] | ||
| ) | ||
|
|
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| if (relatedNodes.length > 0) { | ||
| console.groupCollapsed('Related nodes') | ||
| relatedNodes.forEach(relatedNode => { | ||
| logElement(relatedNode, console.log) | ||
| logHtml(relatedNode) | ||
| }) | ||
| console.groupEnd() | ||
| } | ||
|
|
||
| console.groupEnd() | ||
| } | ||
| } | ||
| } | ||
|
|
||
| export default AxeReporter | ||
| export default { AxeObserver, logViolations } |
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