diff --git a/web/utils/typeahead-utils.js b/web/utils/typeahead-utils.js
--- a/web/utils/typeahead-utils.js
+++ b/web/utils/typeahead-utils.js
@@ -149,9 +149,17 @@
   return { top, left };
 }
 
+function leastPositiveResidue(number: number, modulus: number): number {
+  // the smallest positive of x is integer k such that
+  // x is congruent to k (mod n)
+  // in our case we only consider n > 0
+  return number - Math.floor(number / modulus) * modulus;
+}
+
 export {
   webTypeaheadRegex,
   getCaretOffsets,
   getTypeaheadTooltipActions,
   getTypeaheadTooltipPosition,
+  leastPositiveResidue,
 };