Find broken links, missing images, etc in your HTML.
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README.md

broken-link-checker NPM Version Build Status Dependency Status

Find broken links, missing images, etc in your HTML.

Features:

  • Stream-parses local and remote HTML pages
  • Concurrently checks multiple links
  • Supports various HTML elements/attributes, not just <a href>
  • Supports redirects, absolute URLs, relative URLs and <base>
  • Honors robot exclusions
  • Provides detailed information about each link (HTTP and HTML)
  • URL keyword filtering with wildcards
  • Pause/Resume at any time

Installation

Node.js >= 0.10 is required; < 4.0 will need Promise and Object.assign polyfills.

There're two ways to use it:

Command Line Usage

To install, type this at the command line:

npm install broken-link-checker -g

After that, check out the help for available options:

blc --help

A typical site-wide check might look like:

blc http://yoursite.com -ro

Programmatic API

To install, type this at the command line:

npm install broken-link-checker

The rest of this document will assist you with how to use the API.

Classes

blc.HtmlChecker(options, handlers)

Scans an HTML document to find broken links.

  • handlers.complete is fired after the last result or zero results.

  • handlers.html is fired after the HTML document has been fully parsed.

    • tree is supplied by parse5
    • robots is an instance of robot-directives containing any <meta> robot exclusions.
  • handlers.junk is fired with data on each skipped link, as configured in options.

  • handlers.link is fired with the result of each discovered link (broken or not).

  • .clearCache() will remove any cached URL responses. This is only relevant if the cacheResponses option is enabled.

  • .numActiveLinks() returns the number of links with active requests.

  • .numQueuedLinks() returns the number of links that currently have no active requests.

  • .pause() will pause the internal link queue, but will not pause any active requests.

  • .resume() will resume the internal link queue.

  • .scan(html, baseUrl) parses & scans a single HTML document. Returns false when there is a previously incomplete scan (and true otherwise).

    • html can be a stream or a string.
    • baseUrl is the address to which all relative URLs will be made absolute. Without a value, links to relative URLs will output an "Invalid URL" error.
var htmlChecker = new blc.HtmlChecker(options, {
	html: function(tree, robots){},
	junk: function(result){},
	link: function(result){},
	complete: function(){}
});

htmlChecker.scan(html, baseUrl);

blc.HtmlUrlChecker(options, handlers)

Scans the HTML content at each queued URL to find broken links.

  • handlers.end is fired when the end of the queue has been reached.

  • handlers.html is fired after a page's HTML document has been fully parsed.

    • tree is supplied by parse5.
    • robots is an instance of robot-directives containing any <meta> and X-Robots-Tag robot exclusions.
  • handlers.junk is fired with data on each skipped link, as configured in options.

  • handlers.link is fired with the result of each discovered link (broken or not) within the current page.

  • handlers.page is fired after a page's last result, on zero results, or if the HTML could not be retrieved.

  • .clearCache() will remove any cached URL responses. This is only relevant if the cacheResponses option is enabled.

  • .dequeue(id) removes a page from the queue. Returns true on success or an Error on failure.

  • .enqueue(pageUrl, customData) adds a page to the queue. Queue items are auto-dequeued when their requests are complete. Returns a queue ID on success or an Error on failure.

    • customData is optional data that is stored in the queue item for the page.
  • .numActiveLinks() returns the number of links with active requests.

  • .numPages() returns the total number of pages in the queue.

  • .numQueuedLinks() returns the number of links that currently have no active requests.

  • .pause() will pause the queue, but will not pause any active requests.

  • .resume() will resume the queue.

var htmlUrlChecker = new blc.HtmlUrlChecker(options, {
	html: function(tree, robots, response, pageUrl, customData){},
	junk: function(result, customData){},
	link: function(result, customData){},
	page: function(error, pageUrl, customData){},
	end: function(){}
});

htmlUrlChecker.enqueue(pageUrl, customData);

blc.SiteChecker(options, handlers)

Recursively scans (crawls) the HTML content at each queued URL to find broken links.

  • handlers.end is fired when the end of the queue has been reached.

  • handlers.html is fired after a page's HTML document has been fully parsed.

    • tree is supplied by parse5.
    • robots is an instance of robot-directives containing any <meta> and X-Robots-Tag robot exclusions.
  • handlers.junk is fired with data on each skipped link, as configured in options.

  • handlers.link is fired with the result of each discovered link (broken or not) within the current page.

  • handlers.page is fired after a page's last result, on zero results, or if the HTML could not be retrieved.

  • handlers.robots is fired after a site's robots.txt has been downloaded and provides an instance of robots-txt-guard.

  • handlers.site is fired after a site's last result, on zero results, or if the initial HTML could not be retrieved.

  • .clearCache() will remove any cached URL responses. This is only relevant if the cacheResponses option is enabled.

  • .dequeue(id) removes a site from the queue. Returns true on success or an Error on failure.

  • .enqueue(siteUrl, customData) adds [the first page of] a site to the queue. Queue items are auto-dequeued when their requests are complete. Returns a queue ID on success or an Error on failure.

    • customData is optional data that is stored in the queue item for the site.
  • .numActiveLinks() returns the number of links with active requests.

  • .numPages() returns the total number of pages in the queue.

  • .numQueuedLinks() returns the number of links that currently have no active requests.

  • .numSites() returns the total number of sites in the queue.

  • .pause() will pause the queue, but will not pause any active requests.

  • .resume() will resume the queue.

Note: options.filterLevel is used for determining which links are recursive.

var siteChecker = new blc.SiteChecker(options, {
	robots: function(robots, customData){},
	html: function(tree, robots, response, pageUrl, customData){},
	junk: function(result, customData){},
	link: function(result, customData){},
	page: function(error, pageUrl, customData){},
	site: function(error, siteUrl, customData){},
	end: function(){}
});

siteChecker.enqueue(siteUrl, customData);

blc.UrlChecker(options, handlers)

Requests each queued URL to determine if they are broken.

  • handlers.end is fired when the end of the queue has been reached.

  • handlers.link is fired for each result (broken or not).

  • .clearCache() will remove any cached URL responses. This is only relevant if the cacheResponses option is enabled.

  • .dequeue(id) removes a URL from the queue. Returns true on success or an Error on failure.

  • .enqueue(url, baseUrl, customData) adds a URL to the queue. Queue items are auto-dequeued when their requests are completed. Returns a queue ID on success or an Error on failure.

    • baseUrl is the address to which all relative URLs will be made absolute. Without a value, links to relative URLs will output an "Invalid URL" error.
    • customData is optional data that is stored in the queue item for the URL.
  • .numActiveLinks() returns the number of links with active requests.

  • .numQueuedLinks() returns the number of links that currently have no active requests.

  • .pause() will pause the queue, but will not pause any active requests.

  • .resume() will resume the queue.

var urlChecker = new blc.UrlChecker(options, {
	link: function(result, customData){},
	end: function(){}
});

urlChecker.enqueue(url, baseUrl, customData);

Options

options.acceptedSchemes

Type: Array
Default value: ["http","https"]
Will only check links with schemes/protocols mentioned in this list. Any others (except those in excludedSchemes) will output an "Invalid URL" error.

options.cacheExpiryTime

Type: Number
Default Value: 3600000 (1 hour)
The number of milliseconds in which a cached response should be considered valid. This is only relevant if the cacheResponses option is enabled.

options.cacheResponses

Type: Boolean
Default Value: true
URL request results will be cached when true. This will ensure that each unique URL will only be checked once.

options.excludedKeywords

Type: Array
Default value: []
Will not check or output links that match the keywords and glob patterns in this list. The only wildcard supported is *.

This option does not apply to UrlChecker.

options.excludedSchemes

Type: Array
Default value: ["data","geo","javascript","mailto","sms","tel"]
Will not check or output links with schemes/protocols mentioned in this list. This avoids the output of "Invalid URL" errors with links that cannot be checked.

This option does not apply to UrlChecker.

options.excludeExternalLinks

Type: Boolean
Default value: false
Will not check or output external links when true; relative links with a remote <base> included.

This option does not apply to UrlChecker.

options.excludeInternalLinks

Type: Boolean
Default value: false
Will not check or output internal links when true.

This option does not apply to UrlChecker nor SiteChecker's crawler.

options.excludeLinksToSamePage

Type: Boolean
Default value: true
Will not check or output links to the same page; relative and absolute fragments/hashes included.

This option does not apply to UrlChecker.

options.filterLevel

Type: Number
Default value: 1
The tags and attributes that are considered links for checking, split into the following levels:

  • 0: clickable links
  • 1: clickable links, media, iframes, meta refreshes
  • 2: clickable links, media, iframes, meta refreshes, stylesheets, scripts, forms
  • 3: clickable links, media, iframes, meta refreshes, stylesheets, scripts, forms, metadata

Recursive links have a slightly different filter subset. To see the exact breakdown of both, check out the tag map. <base> is not listed because it is not a link, though it is always parsed.

This option does not apply to UrlChecker.

options.honorRobotExclusions

Type: Boolean
Default value: true
Will not scan pages that search engine crawlers would not follow. Such will have been specified with any of the following:

  • <a rel="nofollow" href="…">
  • <area rel="nofollow" href="…">
  • <meta name="robots" content="noindex,nofollow,…">
  • <meta name="googlebot" content="noindex,nofollow,…">
  • <meta name="robots" content="unavailable_after: …">
  • X-Robots-Tag: noindex,nofollow,…
  • X-Robots-Tag: googlebot: noindex,nofollow,…
  • X-Robots-Tag: otherbot: noindex,nofollow,…
  • X-Robots-Tag: unavailable_after: …
  • robots.txt

This option does not apply to UrlChecker.

options.maxSockets

Type: Number
Default value: Infinity
The maximum number of links to check at any given time.

options.maxSocketsPerHost

Type: Number
Default value: 1
The maximum number of links per host/port to check at any given time. This avoids overloading a single target host with too many concurrent requests. This will not limit concurrent requests to other hosts.

options.rateLimit

Type: Number
Default value: 0
The number of milliseconds to wait before each request.

options.requestMethod

Type: String
Default value: "head"
The HTTP request method used in checking links. If you experience problems, try using "get", however options.retry405Head should have you covered.

options.retry405Head

Type: Boolean
Default value: true
Some servers do not respond correctly to a "head" request method. When true, a link resulting in an HTTP 405 "Method Not Allowed" error will be re-requested using a "get" method before deciding that it is broken.

options.userAgent

Type: String
Default value: "broken-link-checker/0.7.0 Node.js/5.5.0 (OS X El Capitan; x64)" (or similar)
The HTTP user-agent to use when checking links as well as retrieving pages and robot exclusions.

Handling Broken/Excluded Links

A broken link will have a broken value of true and a reason code defined in brokenReason. A link that was not checked (emitted as "junk") will have an excluded value of true and a reason code defined in excludedReason.

if (result.broken) {
	console.log(result.brokenReason);
	//=> HTTP_404
} else if (result.excluded) {
	console.log(result.excludedReason);
	//=> BLC_ROBOTS
}

Additionally, more descriptive messages are available for each reason code:

console.log(blc.BLC_ROBOTS);       //=> Robots Exclusion
console.log(blc.ERRNO_ECONNRESET); //=> connection reset by peer (ECONNRESET)
console.log(blc.HTTP_404);         //=> Not Found (404)

// List all
console.log(blc);

Putting it all together:

if (result.broken) {
	console.log(blc[result.brokenReason]);
} else if (result.excluded) {
	console.log(blc[result.excludedReason]);
}

HTML and HTTP information

Detailed information for each link result is provided. Check out the schema or:

console.log(result);

Roadmap Features

  • fix issue where same-page links are not excluded when cache is enabled, despite excludeLinksToSamePage===true
  • publicize filter handlers
  • add cheerio support by using parse5's htmlparser2 tree adaptor?
  • add rejectUnauthorized:false option to avoid UNABLE_TO_VERIFY_LEAF_SIGNATURE
  • load sitemap.xml at end of each SiteChecker site to possibly check pages that were not linked to
  • remove options.excludedSchemes and handle schemes not in options.acceptedSchemes as junk?
  • change order of checking to: tcp error, 4xx code (broken), 5xx code (undetermined), 200
  • abort download of body when options.retry405Head===true
  • option to retry broken links a number of times (default=0)
  • option to scrape response.body for erroneous sounding text (using fathom?), since an error page could be presented but still have code 200
  • option to check broken link on archive.org for archived version (using this lib)
  • option to run HtmlUrlChecker checks on page load (using jsdom) to include links added with JavaScript?
  • option to check if hashes exist in target URL document?
  • option to parse Markdown in HtmlChecker for links
  • option to play sound when broken link is found
  • option to hide unbroken links
  • option to check plain text URLs
  • add throttle profiles (0–9, -1 for "custom") for easy configuring
  • check ftp:, sftp: (for downloadable files)
  • check mailto:, news:, nntp:, telnet:?
  • check local files if URL is relative and has no base URL?
  • cli json mode -- streamed or not?
  • cli non-tty mode -- change nesting ASCII artwork to time stamps?