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diff --git a/vendor/fivefilters/readability.php/test/test-pages/002/expected.html b/vendor/fivefilters/readability.php/test/test-pages/002/expected.html new file mode 100644 index 0000000..564f9a9 --- /dev/null +++ b/vendor/fivefilters/readability.php/test/test-pages/002/expected.html @@ -0,0 +1,418 @@ +<div id="content-main"> + <article role="article"> + <p>For more than a decade the Web has used XMLHttpRequest (XHR) to achieve + asynchronous requests in JavaScript. While very useful, XHR is not a very + nice API. It suffers from lack of separation of concerns. The input, output + and state are all managed by interacting with one object, and state is + tracked using events. Also, the event-based model doesn’t play well with + JavaScript’s recent focus on Promise- and generator-based asynchronous + programming.</p> + <p>The <a href="https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API">Fetch API</a> intends + to fix most of these problems. It does this by introducing the same primitives + to JS that are used in the HTTP protocol. In addition, it introduces a + utility function <code>fetch()</code> that succinctly captures the intention + of retrieving a resource from the network.</p> + <p>The <a href="https://fetch.spec.whatwg.org">Fetch specification</a>, which + defines the API, nails down the semantics of a user agent fetching a resource. + This, combined with ServiceWorkers, is an attempt to:</p> + <ol> + <li>Improve the offline experience.</li> + <li>Expose the building blocks of the Web to the platform as part of the + <a href="https://extensiblewebmanifesto.org/">extensible web movement</a>.</li> + </ol> + <p>As of this writing, the Fetch API is available in Firefox 39 (currently + Nightly) and Chrome 42 (currently dev). Github has a <a href="https://github.com/github/fetch">Fetch polyfill</a>.</p> + +<h2>Feature detection</h2> + + <p>Fetch API support can be detected by checking for <code>Headers</code>,<code>Request</code>, <code>Response</code> or <code>fetch</code> on + the <code>window</code> or <code>worker</code> scope.</p> + +<h2>Simple fetching</h2> + + <p>The most useful, high-level part of the Fetch API is the <code>fetch()</code> function. + In its simplest form it takes a URL and returns a promise that resolves + to the response. The response is captured as a <code>Response</code> object.</p> + <div><pre>fetch<span>(</span><span>"/data.json"</span><span>)</span>.<span>then</span><span>(</span><span>function</span><span>(</span>res<span>)</span> <span>{</span> + <span>// res instanceof Response == true.</span> + <span>if</span> <span>(</span>res.<span>ok</span><span>)</span> <span>{</span> + res.<span>json</span><span>(</span><span>)</span>.<span>then</span><span>(</span><span>function</span><span>(</span>data<span>)</span> <span>{</span> + console.<span>log</span><span>(</span>data.<span>entries</span><span>)</span><span>;</span> + <span>}</span><span>)</span><span>;</span> + <span>}</span> <span>else</span> <span>{</span> + console.<span>log</span><span>(</span><span>"Looks like the response wasn't perfect, got status"</span><span>,</span> res.<span>status</span><span>)</span><span>;</span> + <span>}</span> +<span>}</span><span>,</span> <span>function</span><span>(</span>e<span>)</span> <span>{</span> + console.<span>log</span><span>(</span><span>"Fetch failed!"</span><span>,</span> e<span>)</span><span>;</span> +<span>}</span><span>)</span><span>;</span></pre> + </div> + <p>Submitting some parameters, it would look like this:</p> + <div><pre>fetch<span>(</span><span>"http://www.example.org/submit.php"</span><span>,</span> <span>{</span> + method<span>:</span> <span>"POST"</span><span>,</span> + headers<span>:</span> <span>{</span> + <span>"Content-Type"</span><span>:</span> <span>"application/x-www-form-urlencoded"</span> + <span>}</span><span>,</span> + body<span>:</span> <span>"firstName=Nikhil&favColor=blue&password=easytoguess"</span> +<span>}</span><span>)</span>.<span>then</span><span>(</span><span>function</span><span>(</span>res<span>)</span> <span>{</span> + <span>if</span> <span>(</span>res.<span>ok</span><span>)</span> <span>{</span> + alert<span>(</span><span>"Perfect! Your settings are saved."</span><span>)</span><span>;</span> + <span>}</span> <span>else</span> <span>if</span> <span>(</span>res.<span>status</span> <span>==</span> <span>401</span><span>)</span> <span>{</span> + alert<span>(</span><span>"Oops! You are not authorized."</span><span>)</span><span>;</span> + <span>}</span> +<span>}</span><span>,</span> <span>function</span><span>(</span>e<span>)</span> <span>{</span> + alert<span>(</span><span>"Error submitting form!"</span><span>)</span><span>;</span> +<span>}</span><span>)</span><span>;</span></pre> + </div> + <p>The <code>fetch()</code> function’s arguments are the same as those passed + to the + <br> +<code>Request()</code> constructor, so you may directly pass arbitrarily + complex requests to <code>fetch()</code> as discussed below.</p> + +<h2>Headers</h2> + + <p>Fetch introduces 3 interfaces. These are <code>Headers</code>, <code>Request</code> and + <br> +<code>Response</code>. They map directly to the underlying HTTP concepts, + but have + <br>certain visibility filters in place for privacy and security reasons, + such as + <br>supporting CORS rules and ensuring cookies aren’t readable by third parties.</p> + <p>The <a href="https://fetch.spec.whatwg.org/#headers-class">Headers interface</a> is + a simple multi-map of names to values:</p> + <div><pre><span>var</span> content <span>=</span> <span>"Hello World"</span><span>;</span> +<span>var</span> reqHeaders <span>=</span> <span>new</span> Headers<span>(</span><span>)</span><span>;</span> +reqHeaders.<span>append</span><span>(</span><span>"Content-Type"</span><span>,</span> <span>"text/plain"</span> +reqHeaders.<span>append</span><span>(</span><span>"Content-Length"</span><span>,</span> content.<span>length</span>.<span>toString</span><span>(</span><span>)</span><span>)</span><span>;</span> +reqHeaders.<span>append</span><span>(</span><span>"X-Custom-Header"</span><span>,</span> <span>"ProcessThisImmediately"</span><span>)</span><span>;</span></pre> + </div> + <p>The same can be achieved by passing an array of arrays or a JS object + literal + <br>to the constructor:</p> + <div><pre>reqHeaders <span>=</span> <span>new</span> Headers<span>(</span><span>{</span> + <span>"Content-Type"</span><span>:</span> <span>"text/plain"</span><span>,</span> + <span>"Content-Length"</span><span>:</span> content.<span>length</span>.<span>toString</span><span>(</span><span>)</span><span>,</span> + <span>"X-Custom-Header"</span><span>:</span> <span>"ProcessThisImmediately"</span><span>,</span> +<span>}</span><span>)</span><span>;</span></pre> + </div> + <p>The contents can be queried and retrieved:</p> + <div><pre>console.<span>log</span><span>(</span>reqHeaders.<span>has</span><span>(</span><span>"Content-Type"</span><span>)</span><span>)</span><span>;</span> <span>// true</span> +console.<span>log</span><span>(</span>reqHeaders.<span>has</span><span>(</span><span>"Set-Cookie"</span><span>)</span><span>)</span><span>;</span> <span>// false</span> +reqHeaders.<span>set</span><span>(</span><span>"Content-Type"</span><span>,</span> <span>"text/html"</span><span>)</span><span>;</span> +reqHeaders.<span>append</span><span>(</span><span>"X-Custom-Header"</span><span>,</span> <span>"AnotherValue"</span><span>)</span><span>;</span> + +console.<span>log</span><span>(</span>reqHeaders.<span>get</span><span>(</span><span>"Content-Length"</span><span>)</span><span>)</span><span>;</span> <span>// 11</span> +console.<span>log</span><span>(</span>reqHeaders.<span>getAll</span><span>(</span><span>"X-Custom-Header"</span><span>)</span><span>)</span><span>;</span> <span>// ["ProcessThisImmediately", "AnotherValue"]</span> + +reqHeaders.<span>delete</span><span>(</span><span>"X-Custom-Header"</span><span>)</span><span>;</span> +console.<span>log</span><span>(</span>reqHeaders.<span>getAll</span><span>(</span><span>"X-Custom-Header"</span><span>)</span><span>)</span><span>;</span> <span>// []</span></pre> + </div> + <p>Some of these operations are only useful in ServiceWorkers, but they provide + <br>a much nicer API to Headers.</p> + <p>Since Headers can be sent in requests, or received in responses, and have + various limitations about what information can and should be mutable, <code>Headers</code> objects + have a <strong>guard</strong> property. This is not exposed to the Web, but + it affects which mutation operations are allowed on the Headers object. + <br>Possible values are:</p> + <ul> + <li>“none”: default.</li> + <li>“request”: guard for a Headers object obtained from a Request (<code>Request.headers</code>).</li> + <li>“request-no-cors”: guard for a Headers object obtained from a Request + created + <br>with mode “no-cors”.</li> + <li>“response”: naturally, for Headers obtained from Response (<code>Response.headers</code>).</li> + <li>“immutable”: Mostly used for ServiceWorkers, renders a Headers object + <br>read-only.</li> + </ul> + <p>The details of how each guard affects the behaviors of the Headers object + are + <br>in the <a href="https://fetch.spec.whatwg.org">specification</a>. For example, + you may not append or set a “request” guarded Headers’ “Content-Length” + header. Similarly, inserting “Set-Cookie” into a Response header is not + allowed so that ServiceWorkers may not set cookies via synthesized Responses.</p> + <p>All of the Headers methods throw TypeError if <code>name</code> is not a + <a href="https://fetch.spec.whatwg.org/#concept-header-name">valid HTTP Header name</a>. The mutation operations will throw TypeError + if there is an immutable guard. Otherwise they fail silently. For example:</p> + <div><pre><span>var</span> res <span>=</span> Response.<span>error</span><span>(</span><span>)</span><span>;</span> +<span>try</span> <span>{</span> + res.<span>headers</span>.<span>set</span><span>(</span><span>"Origin"</span><span>,</span> <span>"http://mybank.com"</span><span>)</span><span>;</span> +<span>}</span> <span>catch</span><span>(</span>e<span>)</span> <span>{</span> + console.<span>log</span><span>(</span><span>"Cannot pretend to be a bank!"</span><span>)</span><span>;</span> +<span>}</span></pre> + </div> + +<h2>Request</h2> + + <p>The Request interface defines a request to fetch a resource over HTTP. + URL, method and headers are expected, but the Request also allows specifying + a body, a request mode, credentials and cache hints.</p> + <p>The simplest Request is of course, just a URL, as you may do to GET a + resource.</p> + <div><pre><span>var</span> req <span>=</span> <span>new</span> Request<span>(</span><span>"/index.html"</span><span>)</span><span>;</span> +console.<span>log</span><span>(</span>req.<span>method</span><span>)</span><span>;</span> <span>// "GET"</span> +console.<span>log</span><span>(</span>req.<span>url</span><span>)</span><span>;</span> <span>// "http://example.com/index.html"</span></pre> + </div> + <p>You may also pass a Request to the <code>Request()</code> constructor to + create a copy. + <br>(This is not the same as calling the <code>clone()</code> method, which + is covered in + <br>the “Reading bodies” section.).</p> + <div><pre><span>var</span> copy <span>=</span> <span>new</span> Request<span>(</span>req<span>)</span><span>;</span> +console.<span>log</span><span>(</span>copy.<span>method</span><span>)</span><span>;</span> <span>// "GET"</span> +console.<span>log</span><span>(</span>copy.<span>url</span><span>)</span><span>;</span> <span>// "http://example.com/index.html"</span></pre> + </div> + <p>Again, this form is probably only useful in ServiceWorkers.</p> + <p>The non-URL attributes of the <code>Request</code> can only be set by passing + initial + <br>values as a second argument to the constructor. This argument is a dictionary.</p> + <div><pre><span>var</span> uploadReq <span>=</span> <span>new</span> Request<span>(</span><span>"/uploadImage"</span><span>,</span> <span>{</span> + method<span>:</span> <span>"POST"</span><span>,</span> + headers<span>:</span> <span>{</span> + <span>"Content-Type"</span><span>:</span> <span>"image/png"</span><span>,</span> + <span>}</span><span>,</span> + body<span>:</span> <span>"image data"</span> +<span>}</span><span>)</span><span>;</span></pre> + </div> + <p>The Request’s mode is used to determine if cross-origin requests lead + to valid responses, and which properties on the response are readable. + Legal mode values are <code>"same-origin"</code>, <code>"no-cors"</code> (default) + and <code>"cors"</code>.</p> + <p>The <code>"same-origin"</code> mode is simple, if a request is made to another + origin with this mode set, the result is simply an error. You could use + this to ensure that + <br>a request is always being made to your origin.</p> + <div><pre><span>var</span> arbitraryUrl <span>=</span> document.<span>getElementById</span><span>(</span><span>"url-input"</span><span>)</span>.<span>value</span><span>;</span> +fetch<span>(</span>arbitraryUrl<span>,</span> <span>{</span> mode<span>:</span> <span>"same-origin"</span> <span>}</span><span>)</span>.<span>then</span><span>(</span><span>function</span><span>(</span>res<span>)</span> <span>{</span> + console.<span>log</span><span>(</span><span>"Response succeeded?"</span><span>,</span> res.<span>ok</span><span>)</span><span>;</span> +<span>}</span><span>,</span> <span>function</span><span>(</span>e<span>)</span> <span>{</span> + console.<span>log</span><span>(</span><span>"Please enter a same-origin URL!"</span><span>)</span><span>;</span> +<span>}</span><span>)</span><span>;</span></pre> + </div> + <p>The <code>"no-cors"</code> mode captures what the web platform does by default + for scripts you import from CDNs, images hosted on other domains, and so + on. First, it prevents the method from being anything other than “HEAD”, + “GET” or “POST”. Second, if any ServiceWorkers intercept these requests, + they may not add or override any headers except for <a href="https://fetch.spec.whatwg.org/#simple-header">these</a>. + Third, JavaScript may not access any properties of the resulting Response. + This ensures that ServiceWorkers do not affect the semantics of the Web + and prevents security and privacy issues that could arise from leaking + data across domains.</p> + <p><code>"cors"</code> mode is what you’ll usually use to make known cross-origin + requests to access various APIs offered by other vendors. These are expected + to adhere to + <br>the <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS">CORS protocol</a>. + Only a <a href="https://fetch.spec.whatwg.org/#concept-filtered-response-cors">limited set</a> of + headers is exposed in the Response, but the body is readable. For example, + you could get a list of Flickr’s <a href="https://www.flickr.com/services/api/flickr.interestingness.getList.html">most interesting</a> photos + today like this:</p> + <div><pre><span>var</span> u <span>=</span> <span>new</span> URLSearchParams<span>(</span><span>)</span><span>;</span> +u.<span>append</span><span>(</span><span>'method'</span><span>,</span> <span>'flickr.interestingness.getList'</span><span>)</span><span>;</span> +u.<span>append</span><span>(</span><span>'api_key'</span><span>,</span> <span>'<insert api key here>'</span><span>)</span><span>;</span> +u.<span>append</span><span>(</span><span>'format'</span><span>,</span> <span>'json'</span><span>)</span><span>;</span> +u.<span>append</span><span>(</span><span>'nojsoncallback'</span><span>,</span> <span>'1'</span><span>)</span><span>;</span> + +<span>var</span> apiCall <span>=</span> fetch<span>(</span><span>'https://api.flickr.com/services/rest?'</span> <span>+</span> u<span>)</span><span>;</span> + +apiCall.<span>then</span><span>(</span><span>function</span><span>(</span>response<span>)</span> <span>{</span> + <span>return</span> response.<span>json</span><span>(</span><span>)</span>.<span>then</span><span>(</span><span>function</span><span>(</span>json<span>)</span> <span>{</span> + <span>// photo is a list of photos.</span> + <span>return</span> json.<span>photos</span>.<span>photo</span><span>;</span> + <span>}</span><span>)</span><span>;</span> +<span>}</span><span>)</span>.<span>then</span><span>(</span><span>function</span><span>(</span>photos<span>)</span> <span>{</span> + photos.<span>forEach</span><span>(</span><span>function</span><span>(</span>photo<span>)</span> <span>{</span> + console.<span>log</span><span>(</span>photo.<span>title</span><span>)</span><span>;</span> + <span>}</span><span>)</span><span>;</span> +<span>}</span><span>)</span><span>;</span></pre> + </div> + <p>You may not read out the “Date” header since Flickr does not allow it + via + <br> +<code>Access-Control-Expose-Headers</code>.</p> + <div><pre>response.<span>headers</span>.<span>get</span><span>(</span><span>"Date"</span><span>)</span><span>;</span> <span>// null</span></pre> + </div> + <p>The <code>credentials</code> enumeration determines if cookies for the other + domain are + <br>sent to cross-origin requests. This is similar to XHR’s <code>withCredentials</code> + <br>flag, but tri-valued as <code>"omit"</code> (default), <code>"same-origin"</code> and <code>"include"</code>.</p> + <p>The Request object will also give the ability to offer caching hints to + the user-agent. This is currently undergoing some <a href="https://github.com/slightlyoff/ServiceWorker/issues/585">security review</a>. + Firefox exposes the attribute, but it has no effect.</p> + <p>Requests have two read-only attributes that are relevant to ServiceWorkers + <br>intercepting them. There is the string <code>referrer</code>, which is + set by the UA to be + <br>the referrer of the Request. This may be an empty string. The other is + <br> +<code>context</code> which is a rather <a href="https://fetch.spec.whatwg.org/#requestcredentials">large enumeration</a> defining + what sort of resource is being fetched. This could be “image” if the request + is from an + <img>tag in the controlled document, “worker” if it is an attempt to load a + worker script, and so on. When used with the <code>fetch()</code> function, + it is “fetch”.</p> + +<h2>Response</h2> + + <p><code>Response</code> instances are returned by calls to <code>fetch()</code>. + They can also be created by JS, but this is only useful in ServiceWorkers.</p> + <p>We have already seen some attributes of Response when we looked at <code>fetch()</code>. + The most obvious candidates are <code>status</code>, an integer (default + value 200) and <code>statusText</code> (default value “OK”), which correspond + to the HTTP status code and reason. The <code>ok</code> attribute is just + a shorthand for checking that <code>status</code> is in the range 200-299 + inclusive.</p> + <p><code>headers</code> is the Response’s Headers object, with guard “response”. + The <code>url</code> attribute reflects the URL of the corresponding request.</p> + <p>Response also has a <code>type</code>, which is “basic”, “cors”, “default”, + “error” or + <br>“opaque”.</p> + <ul> + <li><code>"basic"</code>: normal, same origin response, with all headers exposed + except + <br>“Set-Cookie” and “Set-Cookie2″.</li> + <li><code>"cors"</code>: response was received from a valid cross-origin request. + <a href="https://fetch.spec.whatwg.org/#concept-filtered-response-cors">Certain headers and the body</a>may be accessed.</li> + <li><code>"error"</code>: network error. No useful information describing + the error is available. The Response’s status is 0, headers are empty and + immutable. This is the type for a Response obtained from <code>Response.error()</code>.</li> + <li><code>"opaque"</code>: response for “no-cors” request to cross-origin + resource. <a href="https://fetch.spec.whatwg.org/#concept-filtered-response-opaque">Severely<br> + restricted</a> + </li> + </ul> + <p>The “error” type results in the <code>fetch()</code> Promise rejecting with + TypeError.</p> + <p>There are certain attributes that are useful only in a ServiceWorker scope. + The + <br>idiomatic way to return a Response to an intercepted request in ServiceWorkers + is:</p> + <div><pre>addEventListener<span>(</span><span>'fetch'</span><span>,</span> <span>function</span><span>(</span>event<span>)</span> <span>{</span> + event.<span>respondWith</span><span>(</span><span>new</span> Response<span>(</span><span>"Response body"</span><span>,</span> <span>{</span> + headers<span>:</span> <span>{</span> <span>"Content-Type"</span> <span>:</span> <span>"text/plain"</span> <span>}</span> + <span>}</span><span>)</span><span>;</span> +<span>}</span><span>)</span><span>;</span></pre> + </div> + <p>As you can see, Response has a two argument constructor, where both arguments + are optional. The first argument is a body initializer, and the second + is a dictionary to set the <code>status</code>, <code>statusText</code> and <code>headers</code>.</p> + <p>The static method <code>Response.error()</code> simply returns an error + response. Similarly, <code>Response.redirect(url, status)</code> returns + a Response resulting in + <br>a redirect to <code>url</code>.</p> + +<h2>Dealing with bodies</h2> + + <p>Both Requests and Responses may contain body data. We’ve been glossing + over it because of the various data types body may contain, but we will + cover it in detail now.</p> + <p>A body is an instance of any of the following types.</p> + <ul> + <li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer">ArrayBuffer</a> + </li> + <li><a href="https://developer.mozilla.org/en-US/docs/Web/API/ArrayBufferView">ArrayBufferView</a> (Uint8Array + and friends)</li> + <li><a href="https://developer.mozilla.org/en-US/docs/Web/API/Blob">Blob</a>/ + <a href="https://developer.mozilla.org/en-US/docs/Web/API/File">File</a> + </li> + <li>string</li> + <li><a href="https://url.spec.whatwg.org/#interface-urlsearchparams">URLSearchParams</a> + </li> + <li><a href="https://developer.mozilla.org/en-US/docs/Web/API/FormData">FormData</a> – + currently not supported by either Gecko or Blink. Firefox expects to ship + this in version 39 along with the rest of Fetch.</li> + </ul> + <p>In addition, Request and Response both offer the following methods to + extract their body. These all return a Promise that is eventually resolved + with the actual content.</p> + <ul> + <li><code>arrayBuffer()</code> + </li> + <li><code>blob()</code> + </li> + <li><code>json()</code> + </li> + <li><code>text()</code> + </li> + <li><code>formData()</code> + </li> + </ul> + <p>This is a significant improvement over XHR in terms of ease of use of + non-text data!</p> + <p>Request bodies can be set by passing <code>body</code> parameters:</p> + <div><pre><span>var</span> form <span>=</span> <span>new</span> FormData<span>(</span>document.<span>getElementById</span><span>(</span><span>'login-form'</span><span>)</span><span>)</span><span>;</span> +fetch<span>(</span><span>"/login"</span><span>,</span> <span>{</span> + method<span>:</span> <span>"POST"</span><span>,</span> + body<span>:</span> form +<span>}</span><span>)</span></pre> + </div> + <p>Responses take the first argument as the body.</p> + <div><pre><span>var</span> res <span>=</span> <span>new</span> Response<span>(</span><span>new</span> File<span>(</span><span>[</span><span>"chunk"</span><span>,</span> <span>"chunk"</span><span>]</span><span>,</span> <span>"archive.zip"</span><span>,</span> + <span>{</span> type<span>:</span> <span>"application/zip"</span> <span>}</span><span>)</span><span>)</span><span>;</span></pre> + </div> + <p>Both Request and Response (and by extension the <code>fetch()</code> function), + will try to intelligently <a href="https://fetch.spec.whatwg.org/#concept-bodyinit-extract">determine the content type</a>. + Request will also automatically set a “Content-Type” header if none is + set in the dictionary.</p> + +<h3>Streams and cloning</h3> + + <p>It is important to realise that Request and Response bodies can only be + read once! Both interfaces have a boolean attribute <code>bodyUsed</code> to + determine if it is safe to read or not.</p> + <div><pre><span>var</span> res <span>=</span> <span>new</span> Response<span>(</span><span>"one time use"</span><span>)</span><span>;</span> +console.<span>log</span><span>(</span>res.<span>bodyUsed</span><span>)</span><span>;</span> <span>// false</span> +res.<span>text</span><span>(</span><span>)</span>.<span>then</span><span>(</span><span>function</span><span>(</span>v<span>)</span> <span>{</span> + console.<span>log</span><span>(</span>res.<span>bodyUsed</span><span>)</span><span>;</span> <span>// true</span> +<span>}</span><span>)</span><span>;</span> +console.<span>log</span><span>(</span>res.<span>bodyUsed</span><span>)</span><span>;</span> <span>// true</span> + +res.<span>text</span><span>(</span><span>)</span>.<span>catch</span><span>(</span><span>function</span><span>(</span>e<span>)</span> <span>{</span> + console.<span>log</span><span>(</span><span>"Tried to read already consumed Response"</span><span>)</span><span>;</span> +<span>}</span><span>)</span><span>;</span></pre> + </div> + <p>This decision allows easing the transition to an eventual <a href="https://streams.spec.whatwg.org/">stream-based</a> Fetch + API. The intention is to let applications consume data as it arrives, allowing + for JavaScript to deal with larger files like videos, and perform things + like compression and editing on the fly.</p> + <p>Often, you’ll want access to the body multiple times. For example, you + can use the upcoming <a href="http://slightlyoff.github.io/ServiceWorker/spec/service_worker/index.html#cache-objects">Cache API</a> to + store Requests and Responses for offline use, and Cache requires bodies + to be available for reading.</p> + <p>So how do you read out the body multiple times within such constraints? + The API provides a <code>clone()</code> method on the two interfaces. This + will return a clone of the object, with a ‘new’ body. <code>clone()</code> MUST + be called before the body of the corresponding object has been used. That + is, <code>clone()</code> first, read later.</p> + <div><pre>addEventListener<span>(</span><span>'fetch'</span><span>,</span> <span>function</span><span>(</span>evt<span>)</span> <span>{</span> + <span>var</span> sheep <span>=</span> <span>new</span> Response<span>(</span><span>"Dolly"</span><span>)</span><span>;</span> + console.<span>log</span><span>(</span>sheep.<span>bodyUsed</span><span>)</span><span>;</span> <span>// false</span> + <span>var</span> clone <span>=</span> sheep.<span>clone</span><span>(</span><span>)</span><span>;</span> + console.<span>log</span><span>(</span>clone.<span>bodyUsed</span><span>)</span><span>;</span> <span>// false</span> + + clone.<span>text</span><span>(</span><span>)</span><span>;</span> + console.<span>log</span><span>(</span>sheep.<span>bodyUsed</span><span>)</span><span>;</span> <span>// false</span> + console.<span>log</span><span>(</span>clone.<span>bodyUsed</span><span>)</span><span>;</span> <span>// true</span> + + evt.<span>respondWith</span><span>(</span>cache.<span>add</span><span>(</span>sheep.<span>clone</span><span>(</span><span>)</span><span>)</span>.<span>then</span><span>(</span><span>function</span><span>(</span>e<span>)</span> <span>{</span> + <span>return</span> sheep<span>;</span> + <span>}</span><span>)</span><span>;</span> +<span>}</span><span>)</span><span>;</span></pre> + </div> + +<h2>Future improvements</h2> + + <p>Along with the transition to streams, Fetch will eventually have the ability + to abort running <code>fetch()</code>es and some way to report the progress + of a fetch. These are provided by XHR, but are a little tricky to fit in + the Promise-based nature of the Fetch API.</p> + <p>You can contribute to the evolution of this API by participating in discussions + on the <a href="https://whatwg.org/mailing-list">WHATWG mailing list</a> and + in the issues in the <a href="https://www.w3.org/Bugs/Public/buglist.cgi?product=WHATWG&component=Fetch&resolution=---">Fetch</a> and + <a href="https://github.com/slightlyoff/ServiceWorker/issues">ServiceWorker</a>specifications.</p> + <p>For a better web!</p> + <p><em>The author would like to thank Andrea Marchesini, Anne van Kesteren and Ben<br> +Kelly for helping with the specification and implementation.</em> + </p> + + </article> + + + </div>
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