1 d3_selectionPrototype.classed = function(name, value) {

     2   var names = name.split(d3_selection_classedWhitespace),

     3       n = names.length,

     4       i = -1;

     5   if (arguments.length > 1) {

     6     while (++i < n) d3_selection_classed.call(this, names[i], value);

     7     return this;

     8   } else {

     9     while (++i < n) if (!d3_selection_classed.call(this, names[i])) return false;

    10     return true;

    11   }

    12 };

    13 

    14 var d3_selection_classedWhitespace = /\s+/g;

    15 

    16 function d3_selection_classed(name, value) {

    17   var re = new RegExp("(^|\\s+)" + d3.requote(name) + "(\\s+|$)", "g");

    18 

    19   // If no value is specified, return the first value.

    20   if (arguments.length < 2) {

    21     var node = this.node();

    22     if (c = node.classList) return c.contains(name);

    23     var c = node.className;

    24     re.lastIndex = 0;

    25     return re.test(c.baseVal != null ? c.baseVal : c);

    26   }

    27 

    28   function classedAdd() {

    29     if (c = this.classList) return c.add(name);

    30     var c = this.className,

    31         cb = c.baseVal != null,

    32         cv = cb ? c.baseVal : c;

    33     re.lastIndex = 0;

    34     if (!re.test(cv)) {

    35       cv = d3_collapse(cv + " " + name);

    36       if (cb) c.baseVal = cv;

    37       else this.className = cv;

    38     }

    39   }

    40 

    41   function classedRemove() {

    42     if (c = this.classList) return c.remove(name);

    43     var c = this.className,

    44         cb = c.baseVal != null,

    45         cv = cb ? c.baseVal : c;

    46     cv = d3_collapse(cv.replace(re, " "));

    47     if (cb) c.baseVal = cv;

    48     else this.className = cv;

    49   }

    50 

    51   function classedFunction() {

    52     (value.apply(this, arguments)

    53         ? classedAdd

    54         : classedRemove).call(this);

    55   }

    56 

    57   return this.each(typeof value === "function"

    58       ? classedFunction : value

    59       ? classedAdd

    60       : classedRemove);

    61 }