Adding src/www/js/localstorage.js

A common interface to localStorage, to store JSON data under a unique prefix.

src/www/js/localstorage.js

@@ -0,0 +1,52 @@
+
+
+// See http://diveintohtml5.info/storage.html
+
+function supports_html5_storage() {
+  try {
+    return 'localStorage' in window && window['localStorage'] !== null;
+  } catch (e) {
+    return false;
+  }
+}
+
+// An interface to localStorage to store JSON data under a unique prefix
+function appLocalStorage(appPrefix,fakeIt) {
+
+    function methods(storage) {
+	return {
+	    get: function (name,def) {
+		var id=appPrefix+name
+		return storage[id] ? JSON.parse(storage[id]) : def;
+	    },
+	    put: function (name,value) {
+		var id=appPrefix+name;
+		storage[id]=JSON.stringify(value);
+	    },
+	    remove: function(name) {
+		var id=appPrefix+name;
+		delete storage[id]
+	    },
+	    ls: function(prefix) {
+		var pre=appPrefix+prefix
+		var files=[]
+		for(var i in storage)
+		    if(hasPrefix(i,pre)) files.push(i.substr(pre.length))
+		files.sort()
+		return files
+	    },
+	    get count() { return this.get("count",0); },
+	    set count(v) { this.put("count",v); }
+	}
+    }
+
+    function get_html5_storage() {
+	try {
+	    return 'localStorage' in window && window['localStorage'] || []
+	} catch (e) {
+	    return []; // fake it
+	}
+    }
+
+    return methods(fakeIt || get_html5_storage())
+}