Add attribute-parsing code to widget constructor.

Handles three cases:

1. data-mkws-config -- argument is a JSON fragment containing any
	number of key=value pairs to be added to the configuration
2. Any other data-mkws-NAME -- argument is a string, and is set as the
	value of the configuration item NAME.
3. Any other attribute NAME that is not one of a hardwired set that are
	recognised and discarded -- argument is a string, and is set
	as the value of the attribute name.

Case 1 is the industrial-strength one that can be used when setting a
complex value, such as a list of facets:
	data-mkws-config='{ "facets": ["xtargets", "author", "subject"] }'
Case 2 is the general-purpose way of setting any string value simply:
	data-mkws-perpage="50"
Case 3 is a simplifying short-cut for case 2:
	perpage="20"

diff --git a/src/mkws-widgets.js b/src/mkws-widgets.js
index 2056c48..c2795db 100644 (file)
--- a/src/mkws-widgets.js
+++ b/src/mkws-widgets.js
@@ -1,5 +1,11 @@
 // Factory function for widget objects.
 function widget($, team, type, node) {
+    // Static register of attributes that do not contribute to config
+    var ignoreAttrs = {
+       id:1, class:1, style:1, name:1, action:1, type:1, size:1,
+       value:1, width:1, valign:1
+    };
+
     var that = {
        team: team,
        type: type,
@@ -16,6 +22,26 @@ function widget($, team, type, node) {
        return '[Widget ' + team.name() + ':' + type + ']';
     };
 
+    for (var i = 0; i < node.attributes.length; i++) {
+       var a = node.attributes[i];
+       if (a.name === 'data-mkws-config') {
+           // Treat as a JSON fragment configuring just this widget
+           log(node + ": parsing config fragment '" + a.value + "'");
+           var data = $.parseJSON(a.value);
+           for (var key in data) {
+               log(node + ": adding config element " + key + "='" + data[key] + "'");
+               that.config[key] = data[key];
+           }
+       } else if (a.name.match (/^data-mkws-/)) {
+           var name = a.name.replace(/^data-mkws-/, '')
+           that.config[name] = a.value;
+           log(node + ": set data-mkws attribute " + name + "='" + a.value + "'");
+       } else if (!ignoreAttrs[a.name]) {
+           that.config[a.name] = a.value;
+           log(node + ": set regular attribute " + a.name + "='" + a.value + "'");
+       }
+    }
+
     var fn = mkws.promotionFunction(type);
     if (fn) {
        fn.call(that);