To use them, first, we need to import them into main. The three. The simplest approach is to import everything from the three. The OrbitControls. Importing this works the same way as importing classes from the core:.
Now the OrbitControls class is available within main. With both the core files and a camera controls plugin, we are ready to start building our app. Not so fast! How do we get our hands on the files in the first place? Well, hopefully a lot faster than that : -Eric.
If you're in Node, Puppeteer is an easy way to work with headless Chrome. Below is an example of doing that. Next, we'll take the ssr function from earlier and beef it up a bit:. Finally, here's the small express server that brings it all together. Users will immediately see posts when they hit the page because the static markup is now part of the response.
To run this example, install the dependencies npm i --save puppeteer express and run the server using Node 8. Client code can use this information to track overall performance of a web app. A perfect use case for Server-Timing is to report how long it takes for headless Chrome to prerender a page! To do that, just add the Server-Timing header to the server response:. What about performance numbers? On one of my apps code , headless Chrome takes about 1s to render the page on the server.
These results are promising. Remember when I said "we didn't make any code changes to the client-side app"? That was a lie. Our Express app takes a request, uses Puppeteer to load the page into headless, and serves the result as a response. But this setup has a problem. The same JS that executes in headless Chrome on the server runs again when the user's browser loads the page on the frontend. We have two places generating markup. Let's fix it. We need to tell the page its HTML is already in place.
If it is, we know the page was SSR'd and can avoid re-adding posts again. Apart from caching the rendered results, there are plenty of interesting optimizations we can make to ssr. Some are quick wins while others may be more speculative. The performance benefits you see may ultimately depend on the types of pages you prerender and the complexity of the app. Right now, the entire page and all of the resources it requests is loaded unconditionally into headless Chrome.
However, we're only interested in two things:. Network requests that don't construct DOM are wasteful. Resources like images, fonts, stylesheets, and media don't participate in building the HTML of a page.
They style and supplement the structure of a page but they don't explicitly create it. The host setter steps are:. If url is null or url has an opaque path , then return. Basic URL parse the given value, with url as url and host state as state override. The hostname getter steps are:. Return url 's host , serialized.
The hostname setter steps are:. Basic URL parse the given value, with url as url and hostname state as state override. The port getter steps are:. If url or url 's port is null, return the empty string. Return url 's port , serialized. The port setter steps are:. If the given value is the empty string, then set url 's port to null. Otherwise, basic URL parse the given value, with url as url and port state as state override.
The pathname getter steps are:. Return the result of URL path serializing url. The pathname setter steps are:. Set url 's path to the empty list. Basic URL parse the given value, with url as url and path start state as state override.
The search getter steps are:. If url is null, or url 's query is either null or the empty string, return the empty string. Return "? The search setter steps are:. If url is null, terminate these steps. If the given value is the empty string, set url 's query to null. Let input be the given value with a single leading "? Set url 's query to the empty string. Basic URL parse input , with null, this element's node document 's document's character encoding , url as url , and query state as state override.
The hash getter steps are:. If url is null, or url 's fragment is either null or the empty string, return the empty string. Return " ", followed by url 's fragment.
The hash setter steps are:. If url is null, then return. If the given value is the empty string, set url 's fragment to null.
Let input be the given value with a single leading " " removed, if any. Set url 's fragment to the empty string. Basic URL parse input , with url as url and fragment state as state override. This is also used by form submission for the form element. The exception for a elements is for compatibility with web content. To get an element's noopener , given an a , area , or form element element and a string target :.
If element 's link types include the noopener or noreferrer keyword, then return true. Return false. To follow the hyperlink created by an element subject , given an optional hyperlinkSuffix default null :. If subject cannot navigate , then return. Let replace be false. Let source be subject 's node document 's browsing context.
Let targetAttributeValue be the empty string. If subject is an a or area element, then set targetAttributeValue to the result of getting an element's target given subject. Let noopener be the result of getting an element's noopener with subject and targetAttributeValue. Let target and windowType be the result of applying the rules for choosing a browsing context given targetAttributeValue , source , and noopener.
If target is null, then return. Parse a URL given subject 's href attribute, relative to subject 's node document. Otherwise, if parsing the URL failed, the user agent may report the error to the user in a user-agent-specific manner, may queue an element task on the DOM manipulation task source given subject to navigate the target browsing context to an error page to report the error, or may ignore the error and do nothing. In any case, the user agent must then return.
If hyperlinkSuffix is non-null, then append it to URL. Let request be a new request whose URL is URL and whose referrer policy is the current state of subject 's referrerpolicy content attribute.
If subject 's link types includes the noreferrer keyword, then set request 's referrer to " no-referrer ". Let historyHandling be " replace " if windowType is not " existing or none "; otherwise, " default ". Unlike many other types of navigations, following hyperlinks does not have special " replace " behavior for when documents are not completely loaded.
This is true for both user-initiated instances of following hyperlinks, as well as script-triggered ones via, e. Queue an element task on the DOM manipulation task source given subject to navigate target to request with historyHandling set to historyHandling and the source browsing context set to source.
To indicate that a resource is intended to be downloaded for use later, rather than immediately used, the download attribute can be specified on the a or area element that creates the hyperlink to that resource.
The attribute can furthermore be given a value, to specify the filename that user agents are to use when storing the resource in a file system. This is to protect users from being made to download sensitive personal or confidential information without their full understanding. The following allowed to download algorithm takes an initiator browsing context and an instantiator browsing context , and returns a boolean indicating whether or not downloading is allowed:.
If the initiator browsing context 's sandboxing flags has the sandboxed downloads browsing context flag set, then return false. If the instantiator browsing context is non-null, and its sandboxing flags has the sandboxed downloads browsing context flag set, then return false.
Optionally, the user agent may return false, if it believes doing so would safeguard the user from a potentially hostile download. Return true. To download the hyperlink created by an element subject , given an optional hyperlinkSuffix default null :.
Run the allowed to download algorithm with the subject 's node document 's browsing context and null. If the algorithm returns false, then return. If parsing the URL fails, the user agent may report the error to the user in a user-agent-specific manner, may navigate to an error page to report the error, or may ignore the error and do nothing. In either case, the user agent must return. Run these steps in parallel :. Let request be a new request whose URL is URL , client is entry settings object , initiator is " download ", destination is the empty string, and whose synchronous flag and use-URL-credentials flag are set.
Handle the result of fetching request as a download. When a user agent is to handle a resource obtained from a fetch as a download , it should provide the user with a way to save the resource for later use, if a resource is successfully obtained. Otherwise, it should report any problems downloading the file to the user.
If the user agent needs a filename for a resource being handled as a download , it should select one using the following algorithm. This algorithm is intended to mitigate security dangers involved in downloading files from untrusted sites, and user agents are strongly urged to follow it.
Let filename be the undefined value. Let resource origin be the origin of the URL of the resource being downloaded, unless that URL's scheme component is data , in which case let resource origin be the same as the interface origin , if any. If there is no interface origin , then let trusted operation be true. Otherwise, let trusted operation be true if resource origin is the same origin as interface origin , and false otherwise.
Let proposed filename have the value of the download attribute of the element of the hyperlink that initiated the download at the time the download was initiated. If trusted operation is true, let filename have the value of proposed filename , and jump to the step labeled sanitize below. Let filename be set to the user's preferred filename or to a filename selected by the user agent, and jump to the step labeled sanitize below.
If the algorithm reaches this step, then a download was begun from a different origin than the resource being downloaded, and the origin did not mark the file as suitable for downloading, and the download was not initiated by the user.
This could be because a download attribute was used to trigger the download, or because the resource in question is not of a type that the user agent supports. This could be dangerous, because, for instance, a hostile server could be trying to get a user to unknowingly download private information and then re-upload it to the hostile server, by tricking the user into thinking the data is from the hostile server.
Thus, it is in the user's interests that the user be somehow notified that the resource in question comes from quite a different source, and to prevent confusion, any suggested filename from the potentially hostile interface origin should be ignored. Sanitize : Optionally, allow the user to influence filename.
For example, a user agent could prompt the user for a filename, potentially providing the value of filename as determined above as a default value. Adjust filename to be suitable for the local file system. For example, this could involve removing characters that are not legal in filenames, or trimming leading and trailing whitespace.
If the platform conventions do not in any way use extensions to determine the types of file on the file system, then return filename as the filename. Let claimed type be the type given by the resource's Content-Type metadata , if any is known. Let named type be the type given by filename 's extension , if any is known.
For the purposes of this step, a type is a mapping of a MIME type to an extension. If named type is consistent with the user's preferences e.
If claimed type and named type are the same type i. If the claimed type is known, then alter filename to add an extension corresponding to claimed type. Otherwise, if named type is known to be potentially dangerous e. This last step would make it impossible to download executables, which might not be desirable.
As always, implementers are forced to balance security and usability in this matter. Return filename as the filename. For the purposes of this algorithm, a file extension consists of any part of the filename that platform conventions dictate will be used for identifying the type of the file. For example, many operating systems use the part of the filename following the last dot ". User agents should ignore any directory or path information provided by the resource itself, its URL , and any download attribute, in deciding where to store the resulting file in the user's file system.
If a hyperlink created by an a or area element has a ping attribute, and the user follows the hyperlink, and the value of the element's href attribute can be parsed , relative to the element's node document , without failure, then the user agent must take the ping attribute's value, split that string on ASCII whitespace , parse each resulting token relative to the element's node document , and then run these steps for each resulting URL record ping URL , ignoring tokens that fail to parse:.
Optionally, return. For example, the user agent might wish to ignore any or all ping URLs in accordance with the user's expressed preferences. Fetch request. This may be done in parallel with the primary fetch, and is independent of the result of that fetch.
Based on the user's preferences, UAs may either ignore the ping attribute altogether, or selectively ignore URLs in the list e. User agents must ignore any entity bodies returned in the responses. User agents may close the connection prematurely once they start receiving a response body.
When the ping attribute is present, user agents should clearly indicate to the user that following the hyperlink will also cause secondary requests to be sent in the background, possibly including listing the actual target URLs. For example, a visual user agent could include the hostnames of the target ping URLs along with the hyperlink's actual URL in a status bar or tooltip.
The ping attribute is redundant with pre-existing technologies like HTTP redirects and JavaScript in allowing web pages to track which off-site links are most popular or allowing advertisers to track click-through rates.
However, the ping attribute provides these advantages to the user over those alternatives:. Thus, while it is possible to track users without this feature, authors are encouraged to use the ping attribute so that the user agent can make the user experience more transparent.
This table is non-normative; the actual definitions for the link types are given in the next few sections. In this section, the term referenced document refers to the resource identified by the element representing the link, and the term current document refers to the resource within which the element representing the link finds itself.
To determine which link types apply to a link , a , area , or form element, the element's rel attribute must be split on ASCII whitespace. The resulting tokens are the keywords for the link types that apply to that element. Except where otherwise specified, a keyword must not be specified more than once per rel attribute.
Some of the sections that follow the table below list synonyms for certain keywords. The indicated synonyms are to be handled as specified by user agents, but must not be used in documents for example, the keyword " copyright ". Keywords that are body-ok affect whether link elements are allowed in the body. The body-ok keywords are dns-prefetch , modulepreload , pingback , preconnect , prefetch , preload , prerender , and stylesheet.
New link types that are to be implemented by web browsers are to be added to this standard. The remainder can be registered as extensions. Chrome Android? WebView Android? Samsung Internet? Opera Android? The alternate keyword may be used with link , a , and area elements. The alternate keyword modifies the meaning of the stylesheet keyword in the way described for that keyword.
The alternate keyword does not create a link of its own. Here, a set of link elements provide some style sheets:. The keyword creates a hyperlink referencing a syndication feed though not necessarily syndicating exactly the same content as the current page. If the user agent has the concept of a default syndication feed, the first such element in tree order should be used as the default.
The following link elements give syndication feeds for a blog:. Such link elements would be used by user agents engaged in feed autodiscovery, with the first being the default where applicable. The following example offers various different syndication feeds to the user, using a elements:.
The keyword creates a hyperlink referencing an alternate representation of the current document. The nature of the referenced document is given by the hreflang , and type attributes. If the alternate keyword is used with the hreflang attribute, and that attribute's value differs from the document element 's language , it indicates that the referenced document is a translation.
If the alternate keyword is used with the type attribute, it indicates that the referenced document is a reformulation of the current document in the specified format. The hreflang and type attributes can be combined when specified with the alternate keyword. The following example shows how you can specify versions of the page that use alternative formats, are aimed at other languages, and that are intended for other media:.
This relationship is transitive — that is, if a document links to two other documents with the link type " alternate ", then, in addition to implying that those documents are alternative representations of the first document, it is also implying that those two documents are alternative representations of each other.
The author keyword may be used with link , a , and area elements. This keyword creates a hyperlink. For a and area elements, the author keyword indicates that the referenced document provides further information about the author of the nearest article element ancestor of the element defining the hyperlink, if there is one, or of the page as a whole, otherwise. For link elements, the author keyword indicates that the referenced document provides further information about the author for the page as a whole.
The "referenced document" can be, and often is, a mailto: URL giving the email address of the author. Synonyms : For historical reasons, user agents must also treat link , a , and area elements that have a rev attribute with the value " made " as having the author keyword specified as a link relationship.
The bookmark keyword may be used with a and area elements. The bookmark keyword gives a permalink for the nearest ancestor article element of the linking element in question, or of the section the linking element is most closely associated with , if there are no ancestor article elements. The following snippet has three permalinks.
A user agent could determine which permalink applies to which part of the spec by looking at where the permalinks are given. The canonical keyword may be used with link element. That helps search engines reduce duplicate content, as described in more detail in The Canonical Link Relation.
The dns-prefetch keyword may be used with link elements. This keyword creates an external resource link. This keyword is body-ok. The dns-prefetch keyword indicates that preemptively performing DNS resolution for the origin of the specified resource is likely to be beneficial, as it is highly likely that the user will require resources located at that origin , and the user experience would be improved by preempting the latency costs associated with DNS resolution. User agents must implement the processing model of the dns-prefetch keyword described in Resource Hints.
There is no default type for resources given by the dns-prefetch keyword. The external keyword may be used with a , area , and form elements. This keyword does not create a hyperlink , but annotates any other hyperlinks created by the element the implied hyperlink, if no other keywords create one.
The external keyword indicates that the link is leading to a document that is not part of the site that the current document forms a part of.
The help keyword may be used with link , a , area , and form elements. For a , area , and form elements, the help keyword indicates that the referenced document provides further help information for the parent of the element defining the hyperlink, and its children. In the following example, the form control has associated context-sensitive help.
The user agent could use this information, for example, displaying the referenced document if the user presses the "Help" or "F1" key. For link elements, the help keyword indicates that the referenced document provides help for the page as a whole.
For a and area elements, on some browsers, the help keyword causes the link to use a different cursor. The specified resource is an icon representing the page or site, and should be used by the user agent when representing the page in the user interface. Icons could be auditory icons, visual icons, or other kinds of icons.
If multiple icons are provided, the user agent must select the most appropriate icon according to the type , media , and sizes attributes. If there are multiple equally appropriate icons, user agents must use the last one declared in tree order at the time that the user agent collected the list of icons. If the user agent tries to use an icon but that icon is determined, upon closer examination, to in fact be inappropriate e. User agents are not required to update icons when the list of icons changes, but are encouraged to do so.
There is no default type for resources given by the icon keyword. However, for the purposes of determining the type of the resource , user agents must expect the resource to be an image. The sizes keywords represent icon sizes in raw pixels as opposed to CSS pixels. An icon that is 50 CSS pixels wide intended for displays with a device pixel density of two device pixels per CSS pixel 2x, dpi would have a width of raw pixels.
This feature does not support indicating that a different resource is to be used for small high-resolution icons vs large low-resolution icons e. To parse and process the attribute's value, the user agent must first split the attribute's value on ASCII whitespace , and must then parse each resulting keyword to determine what it represents.
The any keyword represents that the resource contains a scalable icon, e. Return for that keyword. Let width string be the string before the " x " or " X ". Let height string be the string after the " x " or " X ". Apply the rules for parsing non-negative integers to width string to obtain width.
Apply the rules for parsing non-negative integers to height string to obtain height. The keyword represents that the resource contains a bitmap icon with a width of width device pixels and a height of height device pixels. The keywords specified on the sizes attribute must not represent icon sizes that are not actually available in the linked resource. The linked resource fetch setup steps for this type of linked resource, given a link element el and request request , are:.
Set request 's destination to " image ". Let response be the result of fetching request. Use response 's unsafe response as an icon as if it had been declared using the icon keyword. The following snippet shows the top part of an application with several icons. For historical reasons, the icon keyword may be preceded by the keyword " shortcut ".
The license keyword may be used with link , a , area , and form elements. The license keyword indicates that the referenced document provides the copyright license terms under which the main content of the current document is provided. This specification does not specify how to distinguish between the main content of a document and content that is not deemed to be part of that main content.
The distinction should be made clear to the user. Consider a photo sharing site. A page on that site might describe and show a photograph, and the page might be marked up as follows:.
In this case the license applies to just the photo the main content of the document , not the whole document. In particular not the design of the page itself, which is covered by the copyright given at the bottom of the document. This could be made clearer in the styling e. Synonyms : For historical reasons, user agents must also treat the keyword " copyright " like the license keyword.
Firefox Android? Safari iOS? The manifest keyword may be used with link elements. The manifest keyword indicates the manifest file that provides metadata associated with the current document. There is no default type for resources given by the manifest keyword. When a web application is not installed , the appropriate time to fetch and process the linked resource for this link type is when the user agent deems it necessary.
For example, when the user chooses to install the web application. For an installed web application , the appropriate times to fetch and process the linked resource for this link type are:. When the external resource link is created on a link element that is already browsing-context connected. When the external resource link 's link element becomes browsing-context connected. When the href attribute of the link element of an external resource link that is already browsing-context connected is changed.
In either cases, only the first link element in tree order whose rel attribute contains the token manifest may be used.
A user agent must not delay the load event for this link type. Let context be el 's node document 's browsing context. If context is null, then return false. If context is not a top-level browsing context , then return false. Open the App. Note: An earlier version of this tutorial installed babel-core , babel-preset-env , and babel-preset-react-app.
These packages have since been archived, and the mono repo versions are utilized instead. Note: An earlier version of this tutorial used a. This was a configuration file for Babel 6, but this is no longer the case for Babel 7. Now, we will create a webpack config for the server that uses Babel Loader to transpile the code. Start by creating the webpack. With this configuration, our transpiled server bundle will be output to the server-build folder in a file called index.
We will add dev:build-server , dev:start , and dev scripts to the package. The dev:build-server script sets the environment to "development" and invokes webpack with the configuration file we created earlier. The dev:start script invokes nodemon to serve the built output. Note: You will not need to modify the existing "start" , "build" , "test" , and "eject" scripts in the package.
We use nodemon to restart the server when we make changes to it.
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