Using Javascript in CSS

Question

Is it possible to use Javascript inside CSS   If it is  can you give a simple example

User · Answer

I think what you may be thinking of is expressions or  dynamic properties   which are only supported by IE and let you set a property to the result of a javascript expression  Example   width expression document body clientWidth  gt  800   800px    auto       This code makes IE emulate the max-width property it doesn t support   All things considered  however  avoid using these  They are a bad  bad thing

User · Answer

IE and Firefox both contain ways to execute JavaScript from CSS  As Paolo mentions  one way in IE is the expression technique  but there s also the more obscure HTC behavior  in which a seperate XML that contains your script is loaded via CSS  A similar technique for Firefox exists  using XBL  These techniques don t exectue JavaScript from CSS directly  but the effect is the same    HTC with IE  Use a CSS rule like so   body     behavior url script htc       and within that script htc file have something like    lt PUBLIC COMPONENT TAGNAME  xss  gt      lt PUBLIC ATTACH EVENT  ondocumentready  ONEVENT  main    LITERALCONTENT  false   gt   lt  PUBLIC COMPONENT gt   lt SCRIPT gt     function main              alert  HTC script executed           lt  SCRIPT gt    The HTC file executes the main   function on the event ondocumentready  referring to the HTC document s readiness    XBL with Firefox  Firefox supports a similar XML-script-executing hack  using XBL   Use a CSS rule like so   body     -moz-binding  url script xml mycode       and within your script xml    lt  xml version  1 0   gt   lt bindings xmlns  http   www mozilla org xbl  xmlns html  http   www w3 org 1999 xhtml  gt    lt binding id  mycode  gt     lt implementation gt       lt constructor gt        alert  XBL script executed          lt  constructor gt     lt  implementation gt   lt  binding gt    lt  bindings gt    All of the code within the constructor tag will be executed  a good idea to wrap code in a CDATA section    In both techniques  the code doesn t execute unless the CSS selector matches an element within the document  By using something like body  it will execute immediately on page load

User · Answer

Not in any conventional sense of the phrase  inside CSS

User · Answer

Not in any conventional sense of the phrase  inside CSS

User · Answer

Not in any conventional sense of the phrase  inside CSS

User · Answer

I ran into a similar problem and have developed two standalone tools to accomplish this   CjsSS js is a Vanilla Javascript tool  so no external dependencies  that supports back to IE6   ngCss is an Angular Module Filter Factory  aka  plugin  that supports Angular 1 2   so back to IE8    Both of these tool sets allow you to do this in a STYLE tag or within an external   css file         lt script src  some js  gt  lt  script gt       lt script gt          var mainColor    quot  cccccc quot        lt  script gt         BODY           color      mainColor             And this in your on-page style attributes       lt div style  quot color    mainColor   quot  cjsss  quot  sourceCSS quot  gt blah lt  div gt   or      lt div style  quot color    mainColor   quot  ng-css  quot sourceCSS quot  gt blah lt  div gt   NOTE  In ngCss  you could also do  scope mainColor in place of var mainColor By default  the Javascript is executed in a sandboxed IFRAME  but since you author your own CSS and host it on your own server  just like your   js files  then XSS isn t an issue  But the sandbox provides that much more security and peace of mind  CjsSS js and ngCss fall somewhere in-between the other tools around to accomplish similar tasks   LESS  SASS and Stylus are all Preprocessors only and require you to learn a new language and mangle your CSS  Basically they extended CSS with new language features  All are also limited to plugins developed for each platform while CjsSS js and ngCss both allow you to include any Javascript library via  lt script src  blah js  gt  lt  script gt  straight in your CSS   AbsurdJS saw the same problems and went the exact opposite direction of the Preprocessors above  rather than extending CSS  AbsurdJS created a Javascript library to generate CSS    CjsSS js and ngCss took the middle ground  you already know CSS  you already know Javascript  so just let them work together in a simple  intuitive way

User · Answer

IE supports CSS expressions   width expression document body clientWidth  gt  955    955px    100        but they are not standard and are not portable across browsers  Avoid them if possible  They are deprecated since IE8

User · Answer

This turns out to be a very interesting question   With over a hundred properties being set  you d think that you d be allowed to type     clickable    onclick    alert  hi          in your CSS  and it d work   It s intuitive  it makes so much sense   This would be amazingly useful in monkey-patching dynamically-generated massive UIs     The problem  The CSS police  in their infinite wisdom  have drawn a Chinese wall between presentation and behavior   Any HTML properly labeled on-whatever is intentionally not supported by CSS    Full Properties Table     The best way around this is to use jQuery  which sets up an interpreted engine in the background to execute what you were trying to do with the CSS anyway   See this page  Add Javascript Onclick To  css File   Good luck

User · Answer

IE supports CSS expressions   width expression document body clientWidth  gt  955    955px    100        but they are not standard and are not portable across browsers  Avoid them if possible  They are deprecated since IE8

User · Answer

To facilitate potentially solving your problem given the information you ve provided  I m going to assume you re seeking dynamic CSS  If this is the case  you can use a server-side scripting language to do so  For example  and I absolutely love doing things like this    styles css php   body    margin  0px  font-family  Verdana  background-color   cccccc  background-image  url   lt  php echo  images flag bg      user country     png     gt          This would set the background image to whatever was stored in the  user country variable  This is only one example of dynamic CSS  there are virtually limitless possibilities when combining CSS and server-side code  Another case would be doing something like allowing the user to create a custom theme  storing it in a database  and then using PHP to set various properties  like so   user theme css php   body    background-color   lt  php echo  user theme  BG COLOR      gt   color   lt  php echo  user theme  COLOR      gt   font-family   lt  php echo  user theme  FONT      gt        panel    font-size   lt  php echo  user theme  FONT SIZE      gt   background-image   lt  php echo  user theme  PANEL BG      gt        Once again  though  this is merely an off-the-top-of-the-head example  harnessing the power of dynamic CSS via server-side scripting can lead to some pretty incredible stuff

User · Answer

IE and Firefox both contain ways to execute JavaScript from CSS  As Paolo mentions  one way in IE is the expression technique  but there s also the more obscure HTC behavior  in which a seperate XML that contains your script is loaded via CSS  A similar technique for Firefox exists  using XBL  These techniques don t exectue JavaScript from CSS directly  but the effect is the same    HTC with IE  Use a CSS rule like so   body     behavior url script htc       and within that script htc file have something like    lt PUBLIC COMPONENT TAGNAME  xss  gt      lt PUBLIC ATTACH EVENT  ondocumentready  ONEVENT  main    LITERALCONTENT  false   gt   lt  PUBLIC COMPONENT gt   lt SCRIPT gt     function main              alert  HTC script executed           lt  SCRIPT gt    The HTC file executes the main   function on the event ondocumentready  referring to the HTC document s readiness    XBL with Firefox  Firefox supports a similar XML-script-executing hack  using XBL   Use a CSS rule like so   body     -moz-binding  url script xml mycode       and within your script xml    lt  xml version  1 0   gt   lt bindings xmlns  http   www mozilla org xbl  xmlns html  http   www w3 org 1999 xhtml  gt    lt binding id  mycode  gt     lt implementation gt       lt constructor gt        alert  XBL script executed          lt  constructor gt     lt  implementation gt   lt  binding gt    lt  bindings gt    All of the code within the constructor tag will be executed  a good idea to wrap code in a CDATA section    In both techniques  the code doesn t execute unless the CSS selector matches an element within the document  By using something like body  it will execute immediately on page load

User · Answer

This turns out to be a very interesting question   With over a hundred properties being set  you d think that you d be allowed to type     clickable    onclick    alert  hi          in your CSS  and it d work   It s intuitive  it makes so much sense   This would be amazingly useful in monkey-patching dynamically-generated massive UIs     The problem  The CSS police  in their infinite wisdom  have drawn a Chinese wall between presentation and behavior   Any HTML properly labeled on-whatever is intentionally not supported by CSS    Full Properties Table     The best way around this is to use jQuery  which sets up an interpreted engine in the background to execute what you were trying to do with the CSS anyway   See this page  Add Javascript Onclick To  css File   Good luck

User · Answer

To facilitate potentially solving your problem given the information you ve provided  I m going to assume you re seeking dynamic CSS  If this is the case  you can use a server-side scripting language to do so  For example  and I absolutely love doing things like this    styles css php   body    margin  0px  font-family  Verdana  background-color   cccccc  background-image  url   lt  php echo  images flag bg      user country     png     gt          This would set the background image to whatever was stored in the  user country variable  This is only one example of dynamic CSS  there are virtually limitless possibilities when combining CSS and server-side code  Another case would be doing something like allowing the user to create a custom theme  storing it in a database  and then using PHP to set various properties  like so   user theme css php   body    background-color   lt  php echo  user theme  BG COLOR      gt   color   lt  php echo  user theme  COLOR      gt   font-family   lt  php echo  user theme  FONT      gt        panel    font-size   lt  php echo  user theme  FONT SIZE      gt   background-image   lt  php echo  user theme  PANEL BG      gt        Once again  though  this is merely an off-the-top-of-the-head example  harnessing the power of dynamic CSS via server-side scripting can lead to some pretty incredible stuff

User · Answer

I ran into a similar problem and have developed two standalone tools to accomplish this   CjsSS js is a Vanilla Javascript tool  so no external dependencies  that supports back to IE6   ngCss is an Angular Module Filter Factory  aka  plugin  that supports Angular 1 2   so back to IE8    Both of these tool sets allow you to do this in a STYLE tag or within an external   css file         lt script src  some js  gt  lt  script gt       lt script gt          var mainColor    quot  cccccc quot        lt  script gt         BODY           color      mainColor             And this in your on-page style attributes       lt div style  quot color    mainColor   quot  cjsss  quot  sourceCSS quot  gt blah lt  div gt   or      lt div style  quot color    mainColor   quot  ng-css  quot sourceCSS quot  gt blah lt  div gt   NOTE  In ngCss  you could also do  scope mainColor in place of var mainColor By default  the Javascript is executed in a sandboxed IFRAME  but since you author your own CSS and host it on your own server  just like your   js files  then XSS isn t an issue  But the sandbox provides that much more security and peace of mind  CjsSS js and ngCss fall somewhere in-between the other tools around to accomplish similar tasks   LESS  SASS and Stylus are all Preprocessors only and require you to learn a new language and mangle your CSS  Basically they extended CSS with new language features  All are also limited to plugins developed for each platform while CjsSS js and ngCss both allow you to include any Javascript library via  lt script src  blah js  gt  lt  script gt  straight in your CSS   AbsurdJS saw the same problems and went the exact opposite direction of the Preprocessors above  rather than extending CSS  AbsurdJS created a Javascript library to generate CSS    CjsSS js and ngCss took the middle ground  you already know CSS  you already know Javascript  so just let them work together in a simple  intuitive way

User · Answer

To facilitate potentially solving your problem given the information you ve provided  I m going to assume you re seeking dynamic CSS  If this is the case  you can use a server-side scripting language to do so  For example  and I absolutely love doing things like this    styles css php   body    margin  0px  font-family  Verdana  background-color   cccccc  background-image  url   lt  php echo  images flag bg      user country     png     gt          This would set the background image to whatever was stored in the  user country variable  This is only one example of dynamic CSS  there are virtually limitless possibilities when combining CSS and server-side code  Another case would be doing something like allowing the user to create a custom theme  storing it in a database  and then using PHP to set various properties  like so   user theme css php   body    background-color   lt  php echo  user theme  BG COLOR      gt   color   lt  php echo  user theme  COLOR      gt   font-family   lt  php echo  user theme  FONT      gt        panel    font-size   lt  php echo  user theme  FONT SIZE      gt   background-image   lt  php echo  user theme  PANEL BG      gt        Once again  though  this is merely an off-the-top-of-the-head example  harnessing the power of dynamic CSS via server-side scripting can lead to some pretty incredible stuff

User · Answer

I think what you may be thinking of is expressions or  dynamic properties   which are only supported by IE and let you set a property to the result of a javascript expression  Example   width expression document body clientWidth  gt  800   800px    auto       This code makes IE emulate the max-width property it doesn t support   All things considered  however  avoid using these  They are a bad  bad thing

User · Answer

IE supports CSS expressions   width expression document body clientWidth  gt  955    955px    100        but they are not standard and are not portable across browsers  Avoid them if possible  They are deprecated since IE8

User · Answer

Not in any conventional sense of the phrase  inside CSS

User · Answer

I think what you may be thinking of is expressions or  dynamic properties   which are only supported by IE and let you set a property to the result of a javascript expression  Example   width expression document body clientWidth  gt  800   800px    auto       This code makes IE emulate the max-width property it doesn t support   All things considered  however  avoid using these  They are a bad  bad thing

User · Answer

To facilitate potentially solving your problem given the information you ve provided  I m going to assume you re seeking dynamic CSS  If this is the case  you can use a server-side scripting language to do so  For example  and I absolutely love doing things like this    styles css php   body    margin  0px  font-family  Verdana  background-color   cccccc  background-image  url   lt  php echo  images flag bg      user country     png     gt          This would set the background image to whatever was stored in the  user country variable  This is only one example of dynamic CSS  there are virtually limitless possibilities when combining CSS and server-side code  Another case would be doing something like allowing the user to create a custom theme  storing it in a database  and then using PHP to set various properties  like so   user theme css php   body    background-color   lt  php echo  user theme  BG COLOR      gt   color   lt  php echo  user theme  COLOR      gt   font-family   lt  php echo  user theme  FONT      gt        panel    font-size   lt  php echo  user theme  FONT SIZE      gt   background-image   lt  php echo  user theme  PANEL BG      gt        Once again  though  this is merely an off-the-top-of-the-head example  harnessing the power of dynamic CSS via server-side scripting can lead to some pretty incredible stuff

User · Answer

IE and Firefox both contain ways to execute JavaScript from CSS  As Paolo mentions  one way in IE is the expression technique  but there s also the more obscure HTC behavior  in which a seperate XML that contains your script is loaded via CSS  A similar technique for Firefox exists  using XBL  These techniques don t exectue JavaScript from CSS directly  but the effect is the same    HTC with IE  Use a CSS rule like so   body     behavior url script htc       and within that script htc file have something like    lt PUBLIC COMPONENT TAGNAME  xss  gt      lt PUBLIC ATTACH EVENT  ondocumentready  ONEVENT  main    LITERALCONTENT  false   gt   lt  PUBLIC COMPONENT gt   lt SCRIPT gt     function main              alert  HTC script executed           lt  SCRIPT gt    The HTC file executes the main   function on the event ondocumentready  referring to the HTC document s readiness    XBL with Firefox  Firefox supports a similar XML-script-executing hack  using XBL   Use a CSS rule like so   body     -moz-binding  url script xml mycode       and within your script xml    lt  xml version  1 0   gt   lt bindings xmlns  http   www mozilla org xbl  xmlns html  http   www w3 org 1999 xhtml  gt    lt binding id  mycode  gt     lt implementation gt       lt constructor gt        alert  XBL script executed          lt  constructor gt     lt  implementation gt   lt  binding gt    lt  bindings gt    All of the code within the constructor tag will be executed  a good idea to wrap code in a CDATA section    In both techniques  the code doesn t execute unless the CSS selector matches an element within the document  By using something like body  it will execute immediately on page load

User · Answer

IE supports CSS expressions   width expression document body clientWidth  gt  955    955px    100        but they are not standard and are not portable across browsers  Avoid them if possible  They are deprecated since IE8

User · Answer

IE and Firefox both contain ways to execute JavaScript from CSS  As Paolo mentions  one way in IE is the expression technique  but there s also the more obscure HTC behavior  in which a seperate XML that contains your script is loaded via CSS  A similar technique for Firefox exists  using XBL  These techniques don t exectue JavaScript from CSS directly  but the effect is the same    HTC with IE  Use a CSS rule like so   body     behavior url script htc       and within that script htc file have something like    lt PUBLIC COMPONENT TAGNAME  xss  gt      lt PUBLIC ATTACH EVENT  ondocumentready  ONEVENT  main    LITERALCONTENT  false   gt   lt  PUBLIC COMPONENT gt   lt SCRIPT gt     function main              alert  HTC script executed           lt  SCRIPT gt    The HTC file executes the main   function on the event ondocumentready  referring to the HTC document s readiness    XBL with Firefox  Firefox supports a similar XML-script-executing hack  using XBL   Use a CSS rule like so   body     -moz-binding  url script xml mycode       and within your script xml    lt  xml version  1 0   gt   lt bindings xmlns  http   www mozilla org xbl  xmlns html  http   www w3 org 1999 xhtml  gt    lt binding id  mycode  gt     lt implementation gt       lt constructor gt        alert  XBL script executed          lt  constructor gt     lt  implementation gt   lt  binding gt    lt  bindings gt    All of the code within the constructor tag will be executed  a good idea to wrap code in a CDATA section    In both techniques  the code doesn t execute unless the CSS selector matches an element within the document  By using something like body  it will execute immediately on page load

User · Answer

I think what you may be thinking of is expressions or  dynamic properties   which are only supported by IE and let you set a property to the result of a javascript expression  Example   width expression document body clientWidth  gt  800   800px    auto       This code makes IE emulate the max-width property it doesn t support   All things considered  however  avoid using these  They are a bad  bad thing

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