cssAudio - Activefile-genericCSS - ActiveGeneric - ActiveHTML - ActiveImage - ActiveJS - ActiveSVG - ActiveText - Activefile-genericVideo - ActiveLovehtmlicon-personicon-teamoctocatpop-outspinnerstartv

Pen Settings

CSS Base

Vendor Prefixing

Add External CSS

These stylesheets will be added in this order and before the code you write in the CSS editor. You can also add another Pen here, and it will pull the CSS from it. Try typing "font" or "ribbon" below.

Quick-add: + add another resource

Add External JavaScript

These scripts will run in this order and before the code in the JavaScript editor. You can also link to another Pen here, and it will run the JavaScript from it. Also try typing the name of any popular library.

Quick-add: + add another resource

Code Indentation

     

Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

            
              <link rel="stylesheet" type="text/css" media="all" href="http://aaronbarker.net/cssvars/vars.css?a">
<div class="documentation">
  <h1>CSS Variables Polyfill</h1>
  <p>
    This is an attempt at a very basic <a href="https://drafts.csswg.org/css-variables/">CSS variables (custom properties)</a> polyfil. In reality this is more of a <em>partial</em> polyfill as it will not cover variables inside of variables, DOM scoping or anything else "fancy". Just taking variables declared anywhere in the CSS and
    then re-parsing the CSS for var() statements and replacing them in browsers that don't natively support CSS variables.
  </p>
  <p>According to <a href="http://caniuse.com/#feat=css-variables">caniuse.com</a>, of current browsers only IE, Edge and Opera Mini do not support CSS variables. This polyfil appears to work on all three really well. I don't see why this wouldn't work on older browsers as well, but I haven't been able to test it on them yet.</p>

  <p>As far as we can tell your browser <span class="supports">does <span class="no">not</span> support</span> native CSS variables. <span class="showforpolyfill">That means if you see green tests results below, it is thanks to the polyfill :).</span> <span class="hideforpolyfill">All the green test results below are actually native CSS Variable support.  Good job using a good browser :)</span></p>
  
  <h3>Does this work on externally CSS files?</h3>
  <p>Yes!</p>
  <h3>Even ones loaded from another domain?</h3>
  <p>To go across domain, CSS needs to be served up with <code>Access-Control-Allow-Origin:*</code> headers.</p>


</div>
<a href="#d" class="hide-docs">Toggle documentation</a> (for Opera Mini vs Codepen issue)
<style>
  :root {
    --newcolor: #0f0;
  }
  
  .inlineoverlink {
    color: var(--success2);
  }
</style>
<h2>Tests</h2>
<p>On mosts tests (unless otherwise noted) success will be green text. We start with a <code>color:red;</code> and then override it with a <code>color:var(--success);</code> (or similar) which is green.</p>
<span class="samename">declare same variable over and over</span>
<span class="demo1">no whitespace on var() calls</span>
<span class="demo2">whitespace on var() calls</span>
<span class="demo3">Multiple variables in same call. orange means first var worked, green var worked</span>
<span class="inlineoverlink">orange if link won, green if style after link won</span>
<span class="lower">--foo: lowercase foo</span>
<span class="upper">--FOO: uppercase FOO</span>
<span class="fallback">uses fallback <code>--var(--wrongname, green)</code></span>

<h2>Tests on external, cross-domain file</h2>
<div class="documentation">
  <p><strong>Edge</strong> appears to be working well on Edge 13. Edge 12 was having some problems.</p>
  <p><strong>Opera mini</strong> seems to work well too. This demo fails because not all the page is displayed, but I think that is a codepen issue, not a polyfill issue.  When the upper documentation is removed, all tests display well.</p>
  <p><strong>IE 11</strong> seems to do fine.</p>
</div>

<span class="demo4">Gets stuff from external .css file. Should start red and change to green on LINK load. border proves the CSS loaded, missing colors means script didn't get parsed and reinserted</span>
<span class="externalcolor">--externalcolor: should start red and change to green on LINK load</span>
<span class="externalfallback">uses fallback. should be green</span>

<p>Another set of text under the test for Opera Mini testing.</p>
            
          
!
            
              :root {
  --externalcolor: red;
  --samename: orange;
  --samename: #0f0;
  --foo: green;
  --FOO: #0f0;
  --halfsuccess: orange;
  --success: green;
  --success2: #0f0;
}
html {
  font-family: var(--fontsans);
}
.success {
  color: green;
}

.fail {
  color: red;
}

span {
  display: inline-block;
  margin: 5px;
}

.samename {
  color: var(--samename);
}

.demo1 {
  color: #f00;
  color: var(--success);
}

.demo2 {
  color: #f00;
  color: var( --success2);
}

.demo3 {
  color: #f00;
  color: var(--halfsuccess);
  color: var(--success);
}

.demo4 {
  color: red;
  border-color: #f00;
}

.inlineoverlink {
  color: #f00;
}

p {
  padding: var(--spacing-l);
}

.lower {
  color: var(--foo);
}

.upper {
  color: var(--FOO);
}

.externalcolor {
  color: var(--externalcolor);
}

.fallback {
  color: #f00;
  color: var(--wrongname, green);
}

// for the top documentation
.supports {
  color: green;
  .no {
    display:none;
  }
}
.showforpolyfill {
  display:none;
}

.cssvars-polyfilled {
  .supports {
    color: red;
    .no {
      display:inline;
    }
  }
  .showforpolyfill {
    display:inline;
  }
  .hideforpolyfill {
    display:none;
  }
} 
.hide,
.hide-the-docs .documentation {
  display:none;
}
/* declare some font-family stuff at bottom of file to reflect on stuff above it*/

:root {
  --fontsans: arial;
}
            
          
!
            
              /*
TODO:
X Maybe account for defaults: color: var(--header-color, blue);
- Verify cross domain working or not (it is working from dropbox)
- Option to wait to apply anything until all <link>s are parsed or inject what we have and update as each <link> returns
- Need to test on a more complex CSS file
- Option to save parsed file in local/session storage so there isn't a delay on additional page loads. Could only do it for links (with URLs to use as keys) and style blocks with IDs of some sort
- Need to test more complex values like rgba(255,0,0,0.5); and something with !important
- Try multiple links
- Local links
- Ajax driven site, or CSS added later the top of the stack
*/
let cssVarPoly = {
  init() {
    // first lets see if the browser supports CSS variables
    // No version of IE supports window.CSS.supports, so if that isn't supported in the first place we know CSS variables is not supported
    // Edge supports supports, so check for actual variable support
    if (window.CSS && window.CSS.supports && window.CSS.supports('(--foo: red)')) {
      // this browser does support variables, abort
      console.log('your browser supports CSS variables, aborting and letting the native support handle things.');
      return;
    } else {
      // edge barfs on console statements if the console is not open... lame!
      console.log('no support for you! polyfill all (some of) the things!!');
      document.querySelector('body').classList.add('cssvars-polyfilled');
    }

    cssVarPoly.ratifiedVars = {};
    cssVarPoly.varsByBlock = {};
    cssVarPoly.oldCSS = {};
    
    // start things off
    cssVarPoly.findCSS();
    cssVarPoly.updateCSS();
  },
  
  // find all the css blocks, save off the content, and look for variables
  findCSS() {
    let styleBlocks = document.querySelectorAll('style:not(.inserted),link[type="text/css"]');

    // we need to track the order of the style/link elements when we save off the CSS, set a counter
    let counter = 1;

    // loop through all CSS blocks looking for CSS variables being set
    [].forEach.call(styleBlocks, function(block) {
      // console.log(block.nodeName);
      let theCSS;
      if (block.nodeName === 'STYLE') {
        // console.log("style");
        theCSS = block.innerHTML;
        cssVarPoly.findSetters(theCSS, counter);
      } else if (block.nodeName === 'LINK') {
        // console.log("link");
        cssVarPoly.getLink(block.getAttribute('href'), counter, function(counter, request) {
          cssVarPoly.findSetters(request.responseText, counter);
          cssVarPoly.oldCSS[counter] = request.responseText;
          cssVarPoly.updateCSS();
        });
        theCSS = '';
      }
      // save off the CSS to parse through again later. the value may be empty for links that are waiting for their ajax return, but this will maintain the order
      cssVarPoly.oldCSS[counter] = theCSS;
      counter++;
    });
  },

  // find all the "--variable: value" matches in a provided block of CSS and add them to the master list
  findSetters(theCSS, counter) {
    // console.log(theCSS);
    cssVarPoly.varsByBlock[counter] = theCSS.match(/(--.+:.+;)/g) || [];
  },

  // run through all the CSS blocks to update the variables and then inject on the page
  updateCSS() {
    // first lets loop through all the variables to make sure later vars trump earlier vars
    cssVarPoly.ratifySetters(cssVarPoly.varsByBlock);

    // loop through the css blocks (styles and links)
    for (let curCSSID in cssVarPoly.oldCSS) {
      // console.log("curCSS:",oldCSS[curCSSID]);
      let newCSS = cssVarPoly.replaceGetters(cssVarPoly.oldCSS[curCSSID], cssVarPoly.ratifiedVars);
      // put it back into the page
      // first check to see if this block exists already
      if (document.querySelector('#inserted' + curCSSID)) {
        // console.log("updating")
        document.querySelector('#inserted' + curCSSID).innerHTML = newCSS;
      } else {
        // console.log("adding");
        var style = document.createElement('style');
        style.type = 'text/css';
        style.innerHTML = newCSS;
        style.classList.add('inserted');
        style.id = 'inserted' + curCSSID;
        document.getElementsByTagName('head')[0].appendChild(style);
      }
    };
  },

  // parse a provided block of CSS looking for a provided list of variables and replace the --var-name with the correct value
  replaceGetters(curCSS, varList) {
    // console.log(varList);
    for (let theVar in varList) {
      // console.log(theVar);
      // match the variable with the actual variable name
      let getterRegex = new RegExp('var\\(\\s*' + theVar + '\\s*\\)', 'g');
      // console.log(getterRegex);
      // console.log(curCSS);
      curCSS = curCSS.replace(getterRegex, varList[theVar]);

      // now check for any getters that are left that have fallbacks
      let getterRegex2 = new RegExp('var\\(\\s*.+\\s*,\\s*(.+)\\)', 'g');
      // console.log(getterRegex);
      // console.log(curCSS);
      let matches = curCSS.match(getterRegex2);
      if (matches) {
        // console.log("matches",matches);
        matches.forEach(function(match) {
          // console.log(match.match(/var\(.+,\s*(.+)\)/))
          // find the fallback within the getter
          curCSS = curCSS.replace(match, match.match(/var\(.+,\s*(.+)\)/)[1]);
        });

      }

      // curCSS = curCSS.replace(getterRegex2,varList[theVar]);
    };
    // console.log(curCSS);
    return curCSS;
  },

  // determine the css variable name value pair and track the latest
  ratifySetters(varList) {
    // console.log("varList:",varList);
    // loop through each block in order, to maintain order specificity
    for (let curBlock in varList) {
      let curVars = varList[curBlock];
      // console.log("curVars:",curVars);
      // loop through each var in the block
      curVars.forEach(function(theVar) {
        // console.log(theVar);
        // split on the name value pair separator
        let matches = theVar.split(/:\s*/);
        // console.log(matches);
        // put it in an object based on the varName. Each time we do this it will override a previous use and so will always have the last set be the winner
        // 0 = the name, 1 = the value, strip off the ; if it is there
        cssVarPoly.ratifiedVars[matches[0]] = matches[1].replace(/;/, '');
      });
    };
    // console.log(ratifiedVars);
  },

  // get the CSS file (same domain for now)
  getLink(url, counter, success) {
    var request = new XMLHttpRequest();
    request.open('GET', url, true);
    request.overrideMimeType('text/css;');
    request.onload = function() {
      if (request.status >= 200 && request.status < 400) {
        // Success!
        // console.log(request.responseText);
        if (typeof success === 'function') {
          success(counter, request);
        }
      } else {
        // We reached our target server, but it returned an error
        console.warn('an error was returned from:', url);
      }
    };

    request.onerror = function() {
      // There was a connection error of some sort
      console.warn('we could not get anything from:', url);
    };

    request.send();
  }
  
};

// hash = function(s){
//   return s.split("").reduce(function(a,b){a=((a<<5)-a)+b.charCodeAt(0);return a&a},0);              
// }
cssVarPoly.init();

// export default makeFit;

// stuff for hiding documentation for Opera Mini testing
document.querySelector('.hide-docs').addEventListener('click',function(event){
  event.preventDefault();
  document.querySelector('body').classList.toggle('hide-the-docs');
});
            
          
!
999px
Close

Asset uploading is a PRO feature.

As a PRO member, you can drag-and-drop upload files here to use as resources. Images, Libraries, JSON data... anything you want. You can even edit them anytime, like any other code on CodePen.

Go PRO

Loading ..................

Console