node_modules ignore

server/node_modules/lunr/lib/idf.js

@@ -0,0 +1,21 @@
+/**
+ * A function to calculate the inverse document frequency for
+ * a posting. This is shared between the builder and the index
+ *
+ * @private
+ * @param {object} posting - The posting for a given term
+ * @param {number} documentCount - The total number of documents.
+ */
+lunr.idf = function (posting, documentCount) {
+  var documentsWithTerm = 0
+
+  for (var fieldName in posting) {
+    if (fieldName == '_index') continue // Ignore the term index, its not a field
+    documentsWithTerm += Object.keys(posting[fieldName]).length
+  }
+
+  var x = (documentCount - documentsWithTerm + 0.5) / (documentsWithTerm + 0.5)
+
+  return Math.log(1 + Math.abs(x))
+}
+