List CSS custom properties (CSS Variables)

I’ve set some CSS custom properties in my stylesheet:

:root {
    --bc: #fff;
    --bc-primary: #eee;
    --bc-secondary: #ddd;
}

I can retrieve them individually if I already know the name of the CSS variable like so:

console.log(getComputedStyle(document.body).getPropertyValue('--bc'));

// #fff

But if I wanted to pull a list of CSS variables and their values out, how would that be done?

Answer

Update:

• To catch CORS errors, I added !styleSheet.href && to the first if-statement.

---

One possible solution would be to parse the document.styleSheets, and then split the rules into properties/values

var allCSS = [].slice.call(document.styleSheets)
  .reduce(function(prev, styleSheet) {
    if (!styleSheet.href && styleSheet.cssRules) {
      return prev + [].slice.call(styleSheet.cssRules)
        .reduce(function(prev, cssRule) {        
          if (cssRule.selectorText == ':root') {
            var css = cssRule.cssText.split('{');
            css = css[1].replace('}','').split(';');
            for (var i = 0; i < css.length; i++) {
              var prop = css[i].split(':');
              if (prop.length == 2 && prop[0].indexOf('--') == 1) {
                console.log('Property name: ', prop[0]);
                console.log('Property value:', prop[1]);
              }              
            }
          }
        }, '');
    }
  }, '');

:root {
    --bc: #fff;
    --bc-primary: #eee;
    --bc-secondary: #ddd;
}