What is the standard naming convention for html css ids and classes

Question

Does it depend on the platform you are using  or is there a common convention that most developers suggest follow   There are several options    id  someIdentifier   - looks pretty consistent with javascript code   id  some-identifier  - looks more like html5-like attributes and other things in html  id  some identifier  - looks pretty consistent with ruby code and is still a valid identifier inside of Javascript   I was thinking  1 and  3 above make the most sense because they play nicer with Javascript   Is there a right answer to this

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tl dr   There is no one true answer   You can pick one of the many out there  or create your own standards based on what makes sense  depending upon who you re working with   And it is 100  dependent upon the platform     Original Post  Just one more alternative standard to consider    lt div id  id name  class  class-name  gt  lt  div gt    And in your script   var variableName       id name  class-name      This just uses a camelCase  under score  and hyphen-ation respectively for variables  ids  and classes   I ve read about this standard on a couple of different websites   Although a little redundant in css jquery selectors  redundancies make it easier to catch errors   eg  If you see  unknown name or  unknownName in your CSS file  you know you need to figure out what that s actually referring to     UPDATE 2019   Hyphens are called  kebab-case   underscores are called  snake case   and then you have  TitleCase    pascalCase    I personally dislike hyphens   I originally posted this as one alternative  because the rules are simple    However  Hyphens make selection shortcuts very difficult  double click  ctrl option   left right  and ctrl cmd D in vsCode   Also  class names and file names are the only place where hyphens work  because they re almost always in quotes or in css  etc   But the shortcut thing still applies   In addition to variables  class names  and ids  you also want to look at file name conventions   And Git Branches   My office s coding group actually had a meeting a month or two ago to discuss how we were going to name things   For git branches  we couldn t decide between 321-the issue description or 321 the-issue-description    I wanted 321 theIssueDescription  but my coworkers didn t like that    An Example  to demonstrate working with other peoples  standards     Vue js does have a standard   Actually they have two alternate standards for several of their items   I dislike both of their versions for filenames   They recommend either   path kebab-case vue  or   path TitleCase Vue    The former is harder to rename  unless you re specifically trying to rename part of it   The latter is not good for cross-platform compatibility   I would prefer   path snake case vue    However  when working with other people or existing projects  it s important to follow whatever standard was already laid out   Therefore I go with kebab-case for filenames in Vue  even though I ll totally complain about it   Because not following that means changing a lot of files that vue-cli sets up

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There is no agreed upon naming convention for HTML and CSS  But you could structure your nomenclature around object design  More specifically what I call Ownership and Relationship   Ownership   Keywords that describe the object  could be separated by hyphens      car-new-turned-right   Keywords that describe the object can also fall into four categories  which should be ordered from left to right   Object  Object-Descriptor  Action  and Action-Descriptor      car - a noun  and an object   new - an adjective  and an object-descriptor that describes the object in more detail   turned - a verb  and an action that belongs to the object   right - an adjective  and an action-descriptor that describes the action in more detail     Note  verbs  actions  should be in past-tense  turned  did  ran  etc    Relationship   Objects can also have relationships like parent and child  The Action and Action-Descriptor belongs to the parent object  they don t belong to the child object  For relationships between objects you could use an underscore      car-new-turned-right wheel-left-turned-left         car-new-turned-right  follows the ownership rule    wheel-left-turned-left  follows the ownership rule    car-new-turned-right wheel-left-turned-left  follows the relationship rule       Final notes    Because CSS is case-insensitive  it s better to write all names in lower-case  or upper-case   avoid camel-case or pascal-case as they can lead to ambiguous names  Know when to use a class and when to use an id  It s not just about an id being used once on the web page  Most of the time  you want to use a class and not an id  Web components like  buttons  forms  panels     etc  should always use a class  Id s can easily lead to naming conflicts  and should be used sparingly for namespacing your markup  The above concepts of ownership and relationship apply to naming both classes and ids  and will help you avoid naming conflicts  If you don t like my CSS naming convention  there are several others as well  Structural naming convention  Presentational naming convention  Semantic naming convention  BEM naming convention  OCSS naming convention  etc

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There isn t one   I use underscores all the time  due to hyphens messing up the syntax highlighting of my text editor  Gedit   but that s personal preference   I ve seen all these conventions used all over the place  Use the one that you think is best - the one that looks nicest easiest to read for you  as well as easiest to type because you ll be using it a lot  For example  if you ve got your underscore key on the underside of the keyboard  unlikely  but entirely possible   then stick to hyphens  Just go with what is best for yourself  Additionally  all 3 of these conventions are easily readable  If you re working in a team  remember to keep with the team-specified convention  if any    Update 2012  I ve changed how I program over time  I now use camel case  thisIsASelector  instead of hyphens now  I find the latter rather ugly  Use whatever you prefer  which may easily change over time   Update 2013  It looks like I like to mix things up yearly    After switching to Sublime Text and using Bootstrap for a while  I ve gone back to dashes  To me now they look a lot cleaner than un der scores or camelCase  My original point still stands though  there isn t a standard   Update 2015  An interesting corner case with conventions here is Rust  I really like the language  but the compiler will warn you if you define stuff using anything other than underscore case  You can turn the warning off  but it s interesting the compiler strongly suggests a convention by default  I imagine in larger projects it leads to cleaner code which is no bad thing   Update 2016  you asked for it   I ve adopted the BEM standard for my projects going forward  The class names end up being quite verbose  but I think it gives good structure and reusability to the classes and CSS that goes with them  I suppose BEM is actually a standard  so my no becomes a yes perhaps  but it s still up to you what you decide to use in a project  Most importantly  be consistent with what you choose   Update 2019  you asked for it   After writing no CSS for quite a while  I started working at a place that uses OOCSS in one of their products  I personally find it pretty unpleasant to litter classes everywhere  but not having to jump between HTML and CSS all the time feels quite productive   I m still settled on BEM  though  It s verbose  but the namespacing makes working with it in React components very natural  It s also great for selecting specific elements when browser testing   OOCSS and BEM are just some of the CSS standards out there  Pick one that works for you - they re all full of compromises because CSS just isn t that good   Update 2020  A boring update this year  I m still using BEM  My position hasn t really changed from the 2019 update for the reasons listed above  Use what works for you that scales with your team size and hides as much or as little of CSS  poor featureset as you like

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I just recently started learning XML  The underscore version helps me separate everything XML-related  DOM  XSD  etc   from programming languages like Java  JavaScript  camel case   And I agree with you that using identifiers which are allowed in programming languages looks better   Edit  Might be unrelated  but here is a link for rules and recommendations on naming XML elements which I follow when naming ids  sections  XML Naming Rules  and  Best Naming Practices     http   www w3schools com xml xml elements asp

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I think it is platform dependent  When developing in  Net MVC  I use bootstrap style lower case and hyphens for class names  but for ids I use PascalCase   The reasoning for this is that my views are backed by strongly typed view models  Properties of C  models are pascal case  For the sake of model binding with MVC it makes sense that the names of HTML elements that bind to the model are consistent with the view model properties which are pascal case  For simplicity my ids are use the same naming convention as element names except for radio buttons and check boxes which require unique ids for each element in the named input group

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I suggest you use an underscore instead of a hyphen  -   since       lt form name  myForm  gt     lt input name  myInput  id  my-Id  value  myValue   gt   lt  form gt    lt script gt    var x   document myForm my-Id value    alert x    lt  script gt    you can access the value by id easily in like that  But if you use a hyphen it will cause a syntax error   This is an old sample  but it can work without jquery -    thanks to  jean ralphio  there is work around way to avoid by   var x   document myForm  my-Id   value    Dash-style would be a google code style  but I don t really like it   I would prefer TitleCase for id and camelCase for class

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Another reason why many prefer hyphens in CSS id and class names is functionality    Using keyboard shortcuts like option   left right  or ctrl left right on Windows  to traverse code word by word stops the cursor at each dash  allowing you to precisely traverse the id or class name using keyboard shortcuts  Underscores and camelCase do not get detected and the cursor will drift right over them as if it were all one single word

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There is css amp html style guide by google  which recommends to always use a hyphen  https   google github io styleguide htmlcssguide html ID and Class Name Delimiters

[html] What is the standard naming convention for html/css ids and classes?

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UPDATE 2019

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