added list and text helpers

client/components/utils/lists.jsx

@@ -0,0 +1,28 @@
+
+/** 
+ * Intersect lists: [x | x <- A, x `elem` B]
+ */
+export function intersect(a, b) {
+  let res = [];
+  for (const e of a) {
+    for (const k of b) {
+      if (e==k) {
+        res.push(e);
+        break;
+      }
+    }
+  }
+  return res;
+}
+
+/**
+ * Resolve list with dict: [dict[x]||x | x <- L]
+ */
+export function resolve(dict, list) {
+  let result = [];
+  for (const e of list) {
+    result.push(dict[e]||e); 
+  }
+  return result;
+}
+

client/components/utils/text.jsx

@@ -0,0 +1,19 @@
+
+/**
+ * Join list of words with ',' and provide a glue
+ * for the last element.
+ *
+ * Example:
+ *   humanizedJoin(["foo", "bar", "baz"], "or") ->
+ *   "foo, bar or baz"
+ */
+export function humanizedJoin(list, glue="and") {
+  // Doing this the other way round in one step would be nice.
+  let [last, ...init] = list.reverse();
+  init = init.reverse();
+  if (init.length == 0) {
+    return last;
+  }
+  return init.join(", ") + ` ${glue} ${last}`; 
+}
+