Issue 5353 - Add advanced element hiding filters documentation

pages/filters.html

 title=Writing Adblock Plus filters
 
 
 <p>{{s1 Current Adblock Plus versions allow you to "tweak" your filters in many different ways. This document explains the choices that you have and how they can be used.}}</p>
 
   <p>{{s2 <em>Disclaimer</em>: All filter examples given here are really only examples and are not meant to be used.}}</p>
 
   <h2 id="introduction">{{s3 Introduction to Adblock Plus filters}}</h2>
 
   <p>{{s4 The options described in this section should be enough for users who have to create a filter occasionally.}}</p>
@@ skipping 229 matching lines @@
   useful to filter subscription authors who are extending another filter subscription that they
   cannot change.}} {{s102 For example, the rule <code><fix>##div.textad</fix></code> can be
   disabled on <code><fix>example.com</fix></code> using the exception rule
   <code><fix>example.com#@#div.textad</fix></code>.}} {{s103 The combination of these two
   rules has exactly the same effect as the single rule
   <code><fix>~example.com##div.textad</fix></code>.}} {{s104 It is recommended that you use
   exception rules only when you cannot change an overly general element hiding rule, in all the
   other cases limiting this rule to the necessary domains is preferable.}}
 </p>
 
+<h3 id="elemhide_emulation">{{s112 Advanced element hiding}}</h3>

[kzar, 2017/07/10 13:09:18]

Please give strings human-friendly names when making changes. (The sXX names
were generated automatically when we converted our content from another system.)

[hub, 2017/07/10 14:52:32]

ok.

+
+<p>
+  {{s113 Advanced hiding rules will hide elements that matches the CSS selector directly.}}
+  {{s114 <code><fix>example.com#?#div.textad</fix></code> will directly hide <code><fix>&lt;div&gt;</fix></code> elements with the <code><fix>textad</fix></code> class.}}
+  {{s115 These filters only exist as <a href="#generic-specific">specific filters</a>: a domain is mandatory.}}
+</p>
+<p>
+  {{s116 <a href="#elemhide_exceptions">Exception rules</a> above can be applied to the advanced hiding rules the same way.}}
+</p>
+<p>
+  {{s117 Advanced hiding rules also introduce new pseudo-class selectors for when a plain CSS selector isn't enough.}} {{s117 <code><fix>:-abp-has(selector)</fix></code> will select the element whose content match the enclosed selector.}} {{s118 <code><fix>:-abp-properties(properties)</fix></code> will match elements based on their CSS style properties.}}
+</p>
+<p>
+  {{s118 <code><fix>:-abp-properties(properties)</fix></code> will select elements based on properties of their stylesheet.}}
+  {{s119 For example, <code><fix>:-abp-properties(width:300px;height:250px;)</fix></code> will select elements that have <code><fix>width</fix></code> and <code><fix>height</fix></code> set to the specified values <code><fix>300px</fix></code> and <code><fix>250px</fix></code> respectively.}}
+  {{s120 The <a href="https://adblockplus.org/development-builds/new-css-property-filter-syntax">older syntax</a> for the filters is deprecated and will be automatically converted to the new format&nbsp;; the syntax to select the style properties remain the same.}}
+</p>
+<p>
+  {{s121 <code><fix>:-abp-has(selector)</fix></code> will select elements based on their content.}}
+  {{s122 For example, <code><fix>:-abp-has(> div > a.advertiser)</fix></code> will select elements that contain as a direct descendant a <code><fix>&lt;div&gt;</fix></code> that contains an <code><fix>&lt;a&gt;</fix></code> with the class <code><fix>advertiser</fix></code>. The inner selector matching determine whether the selection occur. It is important that <code><fix>:-abp-has()</fix></code> be applied to a restricted number of elements to avoid performance issues. Like any regular pseudo-class you can combine it with the CSS selector syntax.}}
+</p>
+
   <h3 id="elemhide_simplified">{{s105 Simplified element hiding syntax}}</h3>
 
   <p>{{s106 Adblock Plus supports simplified element hiding syntax (e.g. <code><fix>#div(id=foo)</fix></code>) for backwards compatibility only. Using this syntax is discouraged, usual CSS selectors are preferred. Support for this syntax might be removed at some point.}}</p>
 
   <h3 id="generic-specific">{{generic-specific-title Generic / Specific filters}}</h3>
 
   <p>{{generic-specific-explanation-p1 With the <code><fix>$generichide</fix></code> and <code><fix>$genericblock</fix></code> filter options the distinction between generic and specific filters becomes important.}}</p>
   <p>{{generic-specific-explanation-p2 We classify a filter to be <strong>specific</strong> if it matches one or more domains or matches a sitekey. If a filter has no domains specified (or only domain exceptions) and no sitekey then it counts as <strong>generic</strong>. For example, <code><fix>example.com##div.textad</fix></code> is a specific filter, whereas both <code><fix>##div.textad</fix></code> and <code><fix>~example.com##div.textad</fix></code> are generic.}}</p>
   <p>{{generic-specific-explanation-p3 Note that with blocking rules the domain must be specified under the $domain option for them to be considered specific. For example, <code><fix>||example.com^</fix></code> is considered generic whereas <code><fix>*/ads/*$domain=example.com</fix></code> is site-specific.}}</p>
 
@@ skipping 11 matching lines @@
   {{s110 The data used for creating the signature is a concatenated list of request variables (namely URI, host and user agent) separated by the <code><fix>NUL</fix></code> character "\0". For example:}}
 </p>
 
 <pre>
   /index.html?q=foo\0www.example.com\0Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:30.0) Gecko/20100101 Firefox/30.0
 </pre>
 
 <p>
   {{s111 Finally, generate the signature for this string by using the signature algorithm SEC_OID_ISO_SHA_WITH_RSA_SIGNATURE (default when using OpenSSL).}}
 </p>