complete redesign: use nodejs on server instead of php - documentation to be updated

nodejs/node_modules/stylus/lib/functions/alpha.js

@@ -0,0 +1,36 @@
+var nodes = require('../nodes')
+  , rgba = require('./rgba');
+
+/**
+ * Return the alpha component of the given `color`,
+ * or set the alpha component to the optional second `value` argument.
+ *
+ * Examples:
+ *
+ *    alpha(#fff)
+ *    // => 1
+ *
+ *    alpha(rgba(0,0,0,0.3))
+ *    // => 0.3
+ *
+ *    alpha(#fff, 0.5)
+ *    // => rgba(255,255,255,0.5)
+ *
+ * @param {RGBA|HSLA} color
+ * @param {Unit} [value]
+ * @return {Unit|RGBA}
+ * @api public
+ */
+
+module.exports = function alpha(color, value){
+  color = color.rgba;
+  if (value) {
+    return rgba(
+      new nodes.Unit(color.r),
+      new nodes.Unit(color.g),
+      new nodes.Unit(color.b),
+      value
+    );
+  }
+  return new nodes.Unit(color.a, '');
+};