Function d3_class

d3-3.2.8/d3.js:193–204

(ctor, properties)

    return k;
  }
  function d3_class(ctor, properties) {
    try {
      for (var key in properties) {
        Object.defineProperty(ctor.prototype, key, {
          value: properties[key],
          enumerable: false
        });
      }
    } catch (e) {
      ctor.prototype = properties;
    }
  }
  d3.map = function(object) {
    var map = new d3_Map();
    if (object instanceof d3_Map) object.forEach(function(key, value) {