Spider React Native Reference Documentation
Spider
Current Version: 11.6.1
Chilkat.Spider
Initialize the spider with a domain and crawl only URLs that belong to
that same domain.
Add starting URLs, crawl the next queued URL, skip selected URLs, and
inspect unspidered, spidered, failed, and outbound URL lists.
Add wildcard avoid patterns, must-match patterns, and outbound-link
avoid patterns to control which URLs are crawled or collected.
Read the last fetched HTML, page title, meta description, meta keywords,
final redirect URL, and last-modified timestamp.
Fetch pages from a Chilkat-managed cache, update the cache, detect when a
page was redirected, and inspect whether the last page came from cache.
Configure user-agent, proxy settings, connect/read timeouts, IPv6
preference, maximum URL length, maximum response size, and abort support.
Crawl a website domain, manage URL queues, filter links, cache pages, and inspect fetched HTML.
Chilkat.Spider crawls pages within a single initialized domain.
It maintains internal lists of unspidered, spidered, failed, and outbound
URLs; fetches one page at a time; extracts same-domain links for continued
crawling; collects outbound links separately; respects robots.txt;
supports wildcard include and avoid patterns; can use a dedicated cache
directory; and exposes the last fetched HTML, title, meta description,
keywords, redirect information, cache status, and last-modified date.
Domain-limited crawling
URL queue management
Filtering rules
Page metadata
Caching and redirects
Network controls
Initialize with the target domain, add one or more starting
URLs with AddUnspidered, optionally add filtering patterns, then
repeatedly call CrawlNext. After each successful crawl, inspect
LastUrl, LastHtml, page metadata, redirect state,
and the URL-list counts to decide whether to continue, skip, recrawl, or
process the page.
Spider is intended for controlled, domain-oriented crawling and
link discovery. Use Chilkat.Http or Chilkat.Rest
when the task is a single HTTP request, API call, form post, or download
rather than a crawl of discovered links.
Object Creation
// npm install @chilkat/react-native react-native-nitro-modules
// (React Native 0.76+ with the New Architecture; then `pod install` for iOS. The Chilkat
// native library is downloaded and verified during the native build -- see the package README.)
import { Chilkat, Spider } from '@chilkat/react-native'
// Once per app start, before any other Chilkat call:
Chilkat.unlockBundle('Anything for 30-day trial') // shorthand for new Global().unlockBundle(..)
const spider = new Spider()
// ... the native object is released when `spider` is garbage collected, or now with spider.dispose()Creates the underlying native Chilkat object. Spider is a Nitro Module HybridObject: use it from the JavaScript thread only (it cannot be passed to a Worklet or another runtime). Every member is synchronous and blocks the JavaScript thread until Chilkat returns; a method that can take a while also exists as a ...Async twin returning a Promise, which runs the same call on a native worker thread so the UI keeps rendering. While such a call is pending, every other call on this object throws, except abort() and assigning onPercentDone / onProgressInfo.
Releases the native object immediately instead of waiting for garbage collection (useful for a large BinData or an open socket). Calling it more than once is harmless; any other use of the object afterwards throws. An object with a pending ...Async call cannot be disposed until the promise settles.
Errors
A method that can fail throws a plain Error: a method whose only outcome is success or failure returns void and throws on failure; a method producing a string or an object returns it and throws where Chilkat would have returned null. The error's message is "Class.method(...): reason", where the reason is the last informative line of the object's lastErrorText, which holds the full Chilkat log of the failed call. A ...Async twin rejects its promise with the same Error instead of throwing. Properties never throw, and methods that answer a question (has..., is..., ...) return a plain boolean.
try {
spider.someMethod(...)
} catch (e) {
console.log((e as Error).message) // Spider.someMethod(...): <reason>
console.log(spider.lastErrorText) // the full Chilkat log of the failed call
}
// The same call without blocking the JavaScript thread:
try {
await spider.someMethodAsync(...)
} catch (e) {
console.log((e as Error).message) // Spider.someMethodAsync: <reason>
}Properties
AbortCurrent
abortCurrent: boolean
When set to true, causes the currently running method to abort. Methods that always finish quickly (i.e.have no length file operations or network communications) are not affected. If no method is running, then this property is automatically reset to false when the next method is called. When the abort occurs, this property is reset to false. Both synchronous and asynchronous method calls can be aborted. (A synchronous method call could be aborted by setting this property from a separate thread.)
AvoidHttps
avoidHttps: boolean
If set the 1 (true) the spider will avoid all HTTPS URLs. The default is 0 (false).
topCacheDir
cacheDir: string
Specifies a cache directory to use for spidering. If either of the FetchFromCache or UpdateCache properties are true, this is the location of the cache to be used. Note: the Internet Explorer, Netscape, and FireFox caches are completely separate from the Chilkat Spider cache directory. You should specify a new and empty directory.
ChopAtQuery
chopAtQuery: boolean
If equal to 1 (true), then the query portion of all URLs are automatically removed when adding to the unspidered list. The default value is 0 (false).
topConnectTimeout
connectTimeout: number
The maximum number of seconds to wait while connecting to an HTTP server.
topDebugLogFilePath
debugLogFilePath: string
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
Domain
readonly domain: string
The domain name that is being spidered. This is the domain previously set in the Initialize method.
topFetchFromCache
fetchFromCache: boolean
If equal to 1 (true) then pages are fetched from cache when possible. If 0, the cache is ignored. The default value is 1. Regardless, if no CacheDir is set then the cache is not used.
FinalRedirectUrl
readonly finalRedirectUrl: string
If the last URL crawled was redirected (as indicated by the WasRedirected property), this property will contain the final redirect URL.
topHeartbeatMs
heartbeatMs: number
The interval in milliseconds between each AbortCheck event callback, which enables an application to abort certain method calls before they complete. By default, HeartbeatMs is set to 0, meaning no AbortCheck event callbacks will trigger.
LastErrorHtml
readonly lastErrorHtml: string
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
readonly lastErrorText: string
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
readonly lastErrorXml: string
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastFromCache
readonly lastFromCache: boolean
Equal to 1 if the last page spidered was fetched from the cache. Otherwise equal to 0.
topLastHtml
readonly lastHtml: string
The HTML text of the last paged fetched by the spider.
topLastHtmlDescription
readonly lastHtmlDescription: string
The HTML META description from the last page fetched by the spider.
LastHtmlKeywords
readonly lastHtmlKeywords: string
LastHtmlTitle
readonly lastHtmlTitle: string
LastMethodSuccess
lastMethodSuccess: boolean
Indicates the success or failure of the most recent method call: true means success, false means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
LastModDateStr
readonly lastModDateStr: string
The last modification date/time (RFC822 format) from the last page fetched by the spider.
topLastUrl
readonly lastUrl: string
The URL of the last page spidered.
topMaxResponseSize
maxResponseSize: number
The maximum HTTP response size allowed. The spider will automatically fail any pages larger than this size. The default value is 250,000 bytes.
MaxUrlLen
maxUrlLen: number
The maximum URL length allowed. URLs longer than this are not added to the unspidered list. The default value is 200.
NumAvoidPatterns
readonly numAvoidPatterns: number
The number of avoid patterns previously set by calling AddAvoidPattern.
topNumFailed
readonly numFailed: number
The number of URLs in the object's failed URL list.
topNumOutboundLinks
readonly numOutboundLinks: number
The number of URLs in the object's outbound links URL list.
topNumSpidered
readonly numSpidered: number
The number of URLs in the object's already-spidered URL list.
topNumUnspidered
readonly numUnspidered: number
PreferIpv6
preferIpv6: boolean
If true, then use IPv6 over IPv4 when both are supported for a particular domain. The default value of this property is false, which will choose IPv4 over IPv6.
ProxyDomain
proxyDomain: string
The domain name of a proxy host if an HTTP proxy is used.
topProxyLogin
proxyLogin: string
If an HTTP proxy is used and it requires authentication, this property specifies the HTTP proxy login.
topProxyPassword
proxyPassword: string
If an HTTP proxy is used and it requires authentication, this property specifies the HTTP proxy password.
topProxyPort
proxyPort: number
The port number of a proxy server if an HTTP proxy is used.
topReadTimeout
readTimeout: number
The maximum number of seconds to wait when reading from an HTTP server.
topUpdateCache
updateCache: boolean
If equal to 1 (true) then pages saved to the cache. If 0, the cache is ignored. The default value is 1. Regardless, if no CacheDir is set then the cache is not used.
UserAgent
userAgent: string
The value of the HTTP user-agent header field to be sent with HTTP requests. This can be set to any desired value, but be aware that some websites may reject requests from unknown user agents.
topVerboseLogging
verboseLogging: boolean
If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
readonly version: string
WasRedirected
readonly wasRedirected: boolean
Indicates whether the last URL crawled was redirected. (true = yes, false = no)
WindDownCount
windDownCount: number
The wind-down phase begins when this number of URLs has been spidered. When in the wind-down phase, no new URLs are added to the unspidered list. The default value is 0 which means that there is NO wind-down phase.
Methods
AddAvoidOutboundLinkPattern
Adds a wildcarded pattern to prevent collecting matching outbound link URLs. For example, if *google* is added, then any outbound links containing the word google will be ignored. The * character matches zero or more of any character.
AddAvoidPattern
Adds a wildcarded pattern to prevent spidering matching URLs. For example, if *register* is added, then any url containing the word register is not spidered. The * character matches zero or more of any character.
AddMustMatchPattern
Adds a wildcarded pattern to limit spidering to only URLs that match the pattern. For example, if */products/* is added, then only URLs containing /products/ are spidered. This is helpful for only spidering a portion of a website. The * character matches zero or more of any character.
AddUnspidered
To begin spidering you must call this method one or more times to provide starting points. It adds a single URL to the object's internal queue of URLs to be spidered.
CanonicalizeUrl
Canonicalizes a URL by doing the following:
- Drops username/password if present.
- Drops fragment if present.
- Converts domain to lowercase.
- Removes port 80 or 443
- Remove default.asp, index.html, index.htm, default.html, index.htm, default.htm, index.php, index.asp, default.php, .cfm, .aspx, ,php3, .pl, .cgi, .txt, .shtml, .phtml
- Remove www. from the domain if present.
Throws an Error on failure (where the description says null is returned, the method throws instead).
ClearFailedUrls
Clears the object's internal list of URLs that could not be downloaded.
topClearOutboundLinks
Clears the object's internal list of outbound URLs that will automatically accumulate while spidering.
topClearSpideredUrls
Clears the object's internal list of already-spidered URLs that will automatically accumulate while spidering.
topCrawlNext
Crawls the next URL in the internal list of unspidered URLs. The URL is moved from the unspidered list to the spidered list. Any new links within the same domain and not yet spidered are added to the unspidered list. (providing that they do not match avoid patterns, etc.) Any new outbound links are added to the outbound URL list.
If successful, the HTML of the downloaded page is available in the LastHtml property. If there are no more URLs left unspidered, the method returns false. Information about the URL crawled is available in the properties LastUrl, LastFromCache, and LastModDate.
Returns normally on success; throws an Error on failure.
CrawlNextAsync
Asynchronous form of CrawlNext: the same call on a native worker thread, so the JavaScript thread (and the UI) stays responsive. Takes the same arguments and resolves with the same result. While the returned Promise is pending, every other call on this object throws (the object is busy), except abort(), which cancels the call, and assigning the onPercentDone / onProgressInfo callbacks, which report its progress.
Note: the onPercentDone and onProgressInfo callbacks run on the JavaScript thread while the promise is pending, so they can update the UI directly. A rejection's message is "Class.methodAsync: reason"; the full log is in lastErrorText.
Returns a Promise that resolves with the synchronous method's result (undefined for a void method) and rejects with an Error where the synchronous method would throw.
FetchRobotsText
Returns the contents of the robots.txt file from the domain being crawled. This spider object will not crawl URLs excluded by robots.txt. If you believe the spider is not behaving correctly, please notify us at support@chilkatsoft.com and provide information detailing a case that allows us to reproduce the problem.
Throws an Error on failure (where the description says null is returned, the method throws instead).
FetchRobotsTextAsync
Asynchronous form of FetchRobotsText: the same call on a native worker thread, so the JavaScript thread (and the UI) stays responsive. Takes the same arguments and resolves with the same result. While the returned Promise is pending, every other call on this object throws (the object is busy), except abort(), which cancels the call, and assigning the onPercentDone / onProgressInfo callbacks, which report its progress.
Note: the onPercentDone and onProgressInfo callbacks run on the JavaScript thread while the promise is pending, so they can update the UI directly. A rejection's message is "Class.methodAsync: reason"; the full log is in lastErrorText.
Returns a Promise that resolves with the synchronous method's result (undefined for a void method) and rejects with an Error where the synchronous method would throw.
GetAvoidPattern
Returns the Nth avoid pattern previously added by calling AddAvoidPattern. Indexing begins at 0.
Throws an Error on failure (where the description says null is returned, the method throws instead).
GetBaseDomain
Returns the second-level + top-level domain of the domain. For example, if domain is xyz.example.com, this returns example.com. For some domains, such as xyz.example.co.uk, the top 3 levels are returned, such as example.co.uk.
Throws an Error on failure (where the description says null is returned, the method throws instead).
GetFailedUrl
Returns the Nth URL in the failed URL list. Indexing begins at 0.
Throws an Error on failure (where the description says null is returned, the method throws instead).
GetOutboundLink
Returns the Nth URL in the outbound link URL list. Indexing begins at 0.
Throws an Error on failure (where the description says null is returned, the method throws instead).
GetSpideredUrl
Returns the Nth URL in the already-spidered URL list. Indexing begins at 0.
Throws an Error on failure (where the description says null is returned, the method throws instead).
GetUnspideredUrl
Returns the Nth URL in the unspidered URL list. Indexing begins at 0.
Throws an Error on failure (where the description says null is returned, the method throws instead).
GetUrlDomain
Returns the domain name part of a URL. For example, if the URL is https://www.chilkatsoft.com/test.asp, then www.chilkatsoft.com is returned.
Throws an Error on failure (where the description says null is returned, the method throws instead).
Initialize
Initializes the object to begin spidering a domain. Calling Initialize clears any patterns added via the AddAvoidOutboundLinkPattern, AddAvoidPattern, and AddMustMatchPattern methods. The domain name passed to this method is what is returned by the Domain property. The spider only crawls URLs within the same domain.
RecrawlLast
Re-crawls the last URL spidered. This helpful when cookies set in a previous page load cause the page to be loaded differently the next time.
Returns normally on success; throws an Error on failure.
RecrawlLastAsync
Asynchronous form of RecrawlLast: the same call on a native worker thread, so the JavaScript thread (and the UI) stays responsive. Takes the same arguments and resolves with the same result. While the returned Promise is pending, every other call on this object throws (the object is busy), except abort(), which cancels the call, and assigning the onPercentDone / onProgressInfo callbacks, which report its progress.
Note: the onPercentDone and onProgressInfo callbacks run on the JavaScript thread while the promise is pending, so they can update the UI directly. A rejection's message is "Class.methodAsync: reason"; the full log is in lastErrorText.
Returns a Promise that resolves with the synchronous method's result (undefined for a void method) and rejects with an Error where the synchronous method would throw.
SkipUnspidered
Moves a URL from the unspidered list to the spidered list. This allows an application to skip a specific URL.
topSleepMs
Suspends the execution of the current thread until the time-out interval elapses.
topEvents
While a method runs, Spider reports progress through two optional callback properties. Assign a function to receive the event, or undefined to stop receiving it. The callbacks are delivered on the JavaScript thread, so they are useful with the ...Async methods: during a synchronous call the JavaScript thread is busy inside Chilkat, and the events can only arrive after it returns.
const spider = new Spider()
spider.onPercentDone = (pct) => setProgress(pct) // pct is 0..100
spider.onProgressInfo = (name, value) => console.log(`${name}: ${value}`)
spider.heartbeatMs = 250 // let abort() take effect within a quarter second
const pending = spider.someMethodAsync(...)
cancelButton.onPress = () => spider.abort() // the promise then rejects
await pendingPercentDone fires when an operation's completion percentage is known; ProgressInfo delivers named progress values (what is reported depends on the class and method). There is no AbortCheck callback: to cancel a pending ...Async call, call abort() on the object. Chilkat notices the request at its next progress check, which happens at least every heartbeatMs milliseconds on the classes that have that property (0, the default, disables the heartbeat, so set it for a responsive cancel), and the promise rejects with Chilkat's abort error. abort() is harmless when nothing is pending.
PercentDone
onPercentDone?: (pctDone: number) => void
This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).
The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.
To abort the operation, set the abort output argument to true. This will cause the method to terminate and return a failure status or corresponding failure value.
Example:
spider.onPercentDone = (pct) => {
// pct ranges from 0 to 100.
setProgress(pct) // runs on the JavaScript thread: React state may be updated directly
}
await spider.someMethodAsync(...)
// To stop an operation from within the callback, call spider.abort()ProgressInfo
onProgressInfo?: (name: string, value: string) => void
This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.
Note: Some Chilkat methods don't fire any ProgressInfo events.
Example:
spider.onProgressInfo = (name, value) => console.log(`${name}: ${value}`)
await spider.someMethodAsync(...)