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

     2   name = d3.ns.qualify(name);

     3 

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

     5   if (arguments.length < 2) {

     6     var node = this.node();

     7     return name.local

     8         ? node.getAttributeNS(name.space, name.local)

     9         : node.getAttribute(name);

    10   }

    11 

    12   function attrNull() {

    13     this.removeAttribute(name);

    14   }

    15 

    16   function attrNullNS() {

    17     this.removeAttributeNS(name.space, name.local);

    18   }

    19 

    20   function attrConstant() {

    21     this.setAttribute(name, value);

    22   }

    23 

    24   function attrConstantNS() {

    25     this.setAttributeNS(name.space, name.local, value);

    26   }

    27 

    28   function attrFunction() {

    29     var x = value.apply(this, arguments);

    30     if (x == null) this.removeAttribute(name);

    31     else this.setAttribute(name, x);

    32   }

    33 

    34   function attrFunctionNS() {

    35     var x = value.apply(this, arguments);

    36     if (x == null) this.removeAttributeNS(name.space, name.local);

    37     else this.setAttributeNS(name.space, name.local, x);

    38   }

    39 

    40   return this.each(value == null

    41       ? (name.local ? attrNullNS : attrNull) : (typeof value === "function"

    42       ? (name.local ? attrFunctionNS : attrFunction)

    43       : (name.local ? attrConstantNS : attrConstant)));

    44 };