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

Features:

• Parses local and remote HTML documents
• Supports various HTML tags/attributes, not just <a href>
• Supports redirects, absolute URLs, relative URLs and <base>
• Provides detailed information about each link (HTTP and HTML)
• URL keyword filtering with wildcards
• Pause/Resume at any time

Node.js >= 0.10 is required. There're two ways to use it:

To install, type this at the command line:

npm install broken-link-checker -g

After that, check out the help for available options:

blc -?

To install, type this at the command line:

npm install broken-link-checker --save-dev

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

Scans an HTML string to find broken links.

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

• 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.

• .numActive() returns the number of active requests.

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

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

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

  • 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, {
	junk: function(result){},
	link: function(result){},
	complete: function(){}
});

htmlChecker.scan(htmlString, baseUrl);

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.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.

• .length() returns the number of pages in the queue.

• .numActive() returns the number of active link requests.

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

• .resume() will resume the queue.

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

htmlUrlChecker.enqueue(pageUrl, customData);

Recursively scans (crawls) the HTML content at each queued URL to find broken links, while honoring robots.txt exclusions.

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

• 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.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.

• .length() returns the number of sites in the queue.

• .numActive() returns the number of active link requests.

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

• .resume() will resume the queue.

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

siteChecker.enqueue(siteUrl, customData);

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.

• .length() returns the number of URLs in the queue.

• .numActive() returns the number of 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);

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.

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.

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.

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 only applies to HtmlChecker and HtmlUrlChecker.

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 only applies to HtmlChecker and HtmlUrlChecker.

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

This option only applies to HtmlChecker and HtmlUrlChecker.

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

This option only applies to HtmlChecker and HtmlUrlChecker.

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

This option only applies to HtmlChecker and HtmlUrlChecker.

Type: Boolean
Default value: true
Each link's lengthy response data will not be outputted when true.

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
• 2: clickable links, media, stylesheets, scripts, forms
• 3: clickable links, media, stylesheets, scripts, forms, meta

To see the exact breakdown, check out the tag map. <base> is not listed because it is not a link, though it is always parsed.

This option only applies to HtmlChecker and HtmlUrlChecker.

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

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.

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

Type: Boolean
Default value: false
Will enqueue discovered links of the same domain for HTML scanning; also known as performing a site "crawl".

This option only applies to HtmlUrlChecker.

Type: String
Default value: "head"
The HTTP request method used in checking links. Some sites do not respond correctly to "head", while "get" can provide more consistent and accurate results, albeit slower.

Each result will have its own error key for which you can compare against:

if (result.error !== null) {
	// Server denied access
	if (result.error.code === "ECONNREFUSED"){}
	// Server could not be reached
	if (result.error.code === "ENOTFOUND"){}
	// Connection timed out
	if (result.error.code === "ETIMEDOUT"){}
	// Duh.
	if (result.error.message === "Invalid URL"){}
}

• start/end string locations for URL attribute values (parse5#43)
• 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
• option to retry broken links a number of times (default=0)
• option to scrape response.body for erroneous sounding text (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 include iframe HTML source in checking?
• 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
• 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?
• full-site checker/crawler (honoring robots.txt, same-domain and optional same-subdomain)
• cli json mode -- streamed or not?
• cli non-tty mode -- change nesting ASCII artwork to time stamps?
• use ineed?
• stream HTML files (parse5#26)
• MarkdownChecker,MarkdownUrlChecker,HtmlMarkdownChecker,HtmlMarkdownUrlChecker