Uses for the quot entity in HTML

Question

I am revising some XHTML files authored by another party  As part of this effort  I am doing some bulk editing via Linq to XML   I ve just noticed that some of the original source XHTML files contain the  amp quot  HTML entity in text nodes within those files  For instance    lt p gt Greeting   amp quot Hello  World  amp quot  lt  p gt    And that when recovering the XHTML text via XElement ToString    the  amp quot  entities are being replaced by plain double-quotes    lt p gt Greeting   Hello  World   lt  p gt    Question  Can anyone tell me what the motivation might have been for the original author to use the  amp quot  entities instead of plain double-quotes  Did those entities serve a purpose which I don t fully appreciate  Or  were they truly unnecessary as I suspect   I do understand that  amp quot  would be necessary in certain contexts  such as when there is a need to place a double-quote within an HTML attribute  For instance    lt a href   images hello world jpg  alt  Greeting   amp quot Hello  World  amp quot   gt    Greeting lt  a gt

User · Answer

It is likely because they used a single function for escaping attributes and text nodes   amp amp  doesn t do any harm so why complicate your code and make it more error-prone by having two escaping functions and having to pick between them

User · Answer

It is impossible  and unnecessary  to know the motivation for using  amp quot  in element content  but possible motives include  misunderstanding of HTML rules  use of software that generates such code  probably because its author thought it was    safer      and misunderstanding of the meaning of  amp quot   many people seem to think it produces    smart quotes     they apparently never looked at the actual results    Anyway  there is never any need to use  amp quot  in element content in HTML  XHTML or any other HTML version   There is nothing in any HTML specification that would assign any special meaning to the plain character   there   As the question says  it has its role in attribute values  but even in them  it is mostly simpler to just use single quotes as delimiters if the value contains a double quote  e g  alt  Greeting   Hello  World    or  if you are allowed to correct errors in natural language texts  to use proper quotation marks  e g  alt  Greeting     Hello  World

User · Answer

In my experience it may be the result of auto-generation by a string-based tools  where the author did not understand the rules of HTML    When some developers generate HTML without the use of special XML-oriented tools  they may try to be sure the resulting HTML is valid by taking the approach that everything must be escaped    Referring to your example  the reason why every occurrence of   is represented by  amp quot  could be because using that approach  you can safely use such  special  characters in both attributes and values   Another motivation I ve seen is where people believe   We must explicitly show that our symbols are not part of the syntax   Whereas  valid HTML can be created by using the proper string-manipulation tools  see the previous paragraph again   Here is some pseudo-code loosely based on C   although it is preferred to use valid methods and tools   public class HtmlAndXmlWriter       private string Escape string badString                return badString Replace   amp      amp amp    Replace         amp quot    Replace        amp apos    Replace   gt      amp gt    Replace   lt      amp lt                 public string GetHtmlFromOutObject Object obj                return   lt div class  type     Escape obj Type       gt     Escape obj Value      lt  div gt                    It s really very common to see such approaches taken to generate HTML

User · Answer

Reason  1  There was a point where buggy lazy implementations of HTML XHTML renderers were more common than those that got it right   Many years ago  I regularly encountered rendering problems in mainstream browsers resulting from the use of unencoded quote chars in regular text content of HTML XHTML documents   Though the HTML spec has never disallowed use of these chars in text content  it became fairly standard practice to encode them anyway  so that non-spec-compliant browsers and other processors would handle them more gracefully   As a result  many  old-timers  may still do this reflexively   It is not incorrect  though it is now probably unnecessary  unless you re targeting some very archaic platforms   Reason  2  When HTML content is generated dynamically  for example  by populating an HTML template with simple string values from a database  it s necessary to encode each value before embedding it in the generated content   Some common server-side languages provided a single function for this purpose  which simply encoded all chars that might be invalid in some context within an HTML document   Notably  PHP s htmlspecialchars   function is one such example   Though there are optional arguments to htmlspecialchars   that will cause it to ignore quotes  those arguments were  and are  rarely used by authors of basic template-driven systems   The result is that all  special chars  are encoded everywhere they occur in the generated HTML  without regard for the context in which they occur   Again  this is not incorrect  it s simply unnecessary

User · Answer

As other answers pointed out  it is most likely generated by some tool   But if I were the original author of the file  my answer would be  Consistency    If I am not allowed to put double quotes in my attributes  why put them in the element s content   Why do these specs always have these exceptional cases    If I had to write the HTML spec  I would say All double quotes need to be encoded  Done   Today it is like In attribute values we need to encode double quotes  except when the attribute value itself is defined by single quotes  In the content of elements  double quotes can be  but are not required to be  encoded   And I am surely forgetting some cases here      Double quotes are a keyword of the spec  encode them  Lesser greater than are a keyword of the spec  encode them  etc

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