This gist is for my article on how a Browser implements constructors for DOM objects. It contains a short list of samples that are inserted into the article for pretty printing. Here is the link to the article: http://www.justrog.com/2015/05/constructors-by-construction-in.html

basic_constructors.js

// Per spec configures a location on the global of name Node with a value
// of the instance of the function.
function ANode() {
}

// We derive from Object
ANode.prototype = Object.create(Object.prototype);

// Complete the loop back to ourselves
ANode.prototype.constructor = ANode;

// Add constants
Object.defineProperties(ANode, {
    ELEMENT_NODE: {
        value: 1,
        writable: false,
        configurable: false
    },
});

// Add static methods
Object.defineProperties(ANode, {
    create: {
        value: function create() {
            return {};
        }
    }
});

basic_constructors.webidl

interface ANode {
    const unsigned short ELEMENT_NODE = 1;
    static Node create();
};

constructor_syntax.webidl

[Constructor]
interface XMLHttpRequest {
}

[NamedConstructor=Image(optional unsigned long width, optional unsigned long height)]
interface HTMLImageElement {
}

msapp.webidl

[msInterfaceObjectOnly]
interface MSApp
{
    const DOMString CURRENT = "current";
    const DOMString HIGH    = "high";
    const DOMString NORMAL  = "normal";
    const DOMString IDLE    = "idle";

    static any execAtPriority(MSExecAtPriorityFunctionCallback synchronousCallback, DOMString priority, any... args);
};

nodefilter.webidl

[msInterfaceObjectOnly]
interface NodeFilter
{
    // Constants returned by acceptNode
    const short               FILTER_ACCEPT                  = 1;
    const short               FILTER_REJECT                  = 2;
    const short               FILTER_SKIP                    = 3;

    // Constants for whatToShow
    const unsigned long       SHOW_ALL                       = 0xFFFFFFFF;
    const unsigned long       SHOW_ELEMENT                   = 0x00000001;
    const unsigned long       SHOW_ATTRIBUTE                 = 0x00000002;
    const unsigned long       SHOW_TEXT                      = 0x00000004;
    const unsigned long       SHOW_CDATA_SECTION             = 0x00000008;
    const unsigned long       SHOW_ENTITY_REFERENCE          = 0x00000010;
    const unsigned long       SHOW_ENTITY                    = 0x00000020;
    const unsigned long       SHOW_PROCESSING_INSTRUCTION    = 0x00000040;
    const unsigned long       SHOW_COMMENT                   = 0x00000080;
    const unsigned long       SHOW_DOCUMENT                  = 0x00000100;
    const unsigned long       SHOW_DOCUMENT_TYPE             = 0x00000200;
    const unsigned long       SHOW_DOCUMENT_FRAGMENT         = 0x00000400;
    const unsigned long       SHOW_NOTATION                  = 0x00000800;
    short              acceptNode(Node n); // This API is ignored in the binding
};