diff --git a/client/src/util/typedCrossfilter/bitArray.js b/client/src/util/typedCrossfilter/bitArray.js
index 667f359c..2fa46acb 100644
--- a/client/src/util/typedCrossfilter/bitArray.js
+++ b/client/src/util/typedCrossfilter/bitArray.js
@@ -251,4 +251,4 @@ class BitArray {
   }
 }
 
-module.exports = BitArray;
+export default BitArray;
diff --git a/client/src/util/typedCrossfilter/index.js b/client/src/util/typedCrossfilter/index.js
index 57a4de56..7c19d10b 100644
--- a/client/src/util/typedCrossfilter/index.js
+++ b/client/src/util/typedCrossfilter/index.js
@@ -29,9 +29,15 @@ more complex API.  In a few cases, elements of that API were incorporated.
 
 */
 
-var PositiveIntervals = require("./positiveIntervals");
-var BitArray = require("./bitArray");
-var Util = require("./util");
+import PositiveIntervals from "./positiveIntervals";
+import BitArray from "./bitArray";
+import {
+  fillRange,
+  lowerBound,
+  lowerBoundIndirect,
+  upperBound,
+  upperBoundIndirect
+} from "./util";
 
 class NotImplementedError extends Error {
   constructor(...params) {
@@ -129,7 +135,7 @@ class ScalarDimension {
     this.value = array;
 
     // create sort index
-    this.index = Util.fillRange(new Uint32Array(this.crossfilter.data.length));
+    this.index = fillRange(new Uint32Array(this.crossfilter.data.length));
     this.index.sort((a, b) => array[a] - array[b]);
 
     // groups, if any
@@ -193,20 +199,8 @@ class ScalarDimension {
   // filter by value - exact match
   filterExact(value) {
     const newFilter = [
-      Util.lowerBoundIndirect(
-        this.value,
-        this.index,
-        value,
-        0,
-        this.value.length
-      ),
-      Util.upperBoundIndirect(
-        this.value,
-        this.index,
-        value,
-        0,
-        this.value.length
-      )
+      lowerBoundIndirect(this.value, this.index, value, 0, this.value.length),
+      upperBoundIndirect(this.value, this.index, value, 0, this.value.length)
     ];
     if (newFilter[0] <= newFilter[1]) {
       this._updateFilters([newFilter]);
@@ -221,14 +215,14 @@ class ScalarDimension {
     const newFilter = [];
     for (let v = 0, len = values.length; v < len; v++) {
       const intv = [
-        Util.lowerBoundIndirect(
+        lowerBoundIndirect(
           this.value,
           this.index,
           values[v],
           0,
           this.value.length
         ),
-        Util.upperBoundIndirect(
+        upperBoundIndirect(
           this.value,
           this.index,
           values[v],
@@ -247,20 +241,14 @@ class ScalarDimension {
   filterRange(range) {
     const newFilter = [];
     const intv = [
-      Util.lowerBoundIndirect(
+      lowerBoundIndirect(
         this.value,
         this.index,
         range[0],
         0,
         this.value.length
       ),
-      Util.upperBoundIndirect(
-        this.value,
-        this.index,
-        range[1],
-        0,
-        this.value.length
-      )
+      upperBoundIndirect(this.value, this.index, range[1], 0, this.value.length)
     ];
     if (intv[0] < intv[1]) newFilter.push(intv);
     this._updateFilters(newFilter);
@@ -374,7 +362,7 @@ class EnumDimension extends ScalarDimension {
     const enumLen = this.enumIndex.length;
     for (let i = 0; i < len; i++) {
       const v = value(data[i]);
-      const e = Util.lowerBound(this.enumIndex, v, 0, enumLen);
+      const e = lowerBound(this.enumIndex, v, 0, enumLen);
       array[i] = e;
     }
     return array;
@@ -382,23 +370,19 @@ class EnumDimension extends ScalarDimension {
 
   filterExact(value) {
     return super.filterExact(
-      Util.lowerBound(this.enumIndex, value, 0, this.enumIndex.length)
+      lowerBound(this.enumIndex, value, 0, this.enumIndex.length)
     );
   }
 
   filterEnum(values) {
     return super.filterEnum(
-      values.map(v =>
-        Util.lowerBound(this.enumIndex, v, 0, this.enumIndex.length)
-      )
+      values.map(v => lowerBound(this.enumIndex, v, 0, this.enumIndex.length))
     );
   }
 
   filterRange(range) {
     return super.filterEnum(
-      range.map(v =>
-        Util.lowerBound(this.enumIndex, v, 0, this.enumIndex.length)
-      )
+      range.map(v => lowerBound(this.enumIndex, v, 0, this.enumIndex.length))
     );
   }
 
@@ -615,4 +599,4 @@ crossfilter.TypedCrossfilter = TypedCrossfilter;
 crossfilter.ScalarDimension = ScalarDimension;
 crossfilter.EnumDimension = EnumDimension;
 
-module.exports = crossfilter;
+export default crossfilter;
diff --git a/client/src/util/typedCrossfilter/positiveIntervals.js b/client/src/util/typedCrossfilter/positiveIntervals.js
index 6e5d074a..5e54bf7f 100644
--- a/client/src/util/typedCrossfilter/positiveIntervals.js
+++ b/client/src/util/typedCrossfilter/positiveIntervals.js
@@ -129,4 +129,4 @@ class PositiveIntervals {
   }
 }
 
-module.exports = PositiveIntervals;
+export default PositiveIntervals;
diff --git a/client/src/util/typedCrossfilter/util.js b/client/src/util/typedCrossfilter/util.js
index deffcdec..18b2c21e 100644
--- a/client/src/util/typedCrossfilter/util.js
+++ b/client/src/util/typedCrossfilter/util.js
@@ -8,7 +8,7 @@
 // fill an array or typedarray with a sequential range of numbers,
 // starting with `start`
 //
-function fillRange(arr, start = 0) {
+export function fillRange(arr, start = 0) {
   for (let i = 0, len = arr.length; i < len; i++) {
     arr[i] = i + start;
   }
@@ -30,7 +30,7 @@ function fillRange(arr, start = 0) {
 // a factory version of lowerBound that takes an accessor (rather than having
 // a special-cased version for lining the indirection).
 //
-function lowerBound(valueArray, value, first, last) {
+export function lowerBound(valueArray, value, first, last) {
   // this is just a binary search
   while (first < last) {
     const middle = (first + last) >>> 1;
@@ -45,7 +45,7 @@ function lowerBound(valueArray, value, first, last) {
 
 // Inlined performance optimization - used to indirect through a sort map.
 //
-function lowerBoundIndirect(valueArray, indexArray, value, first, last) {
+export function lowerBoundIndirect(valueArray, indexArray, value, first, last) {
   // this is just a binary search
   while (first < last) {
     const middle = (first + last) >>> 1;
@@ -69,7 +69,7 @@ function lowerBoundIndirect(valueArray, indexArray, value, first, last) {
 //    C++: upper_bound()
 //    Python: bisect.bisect_right()
 //
-function upperBound(valueArray, value, first, last) {
+export function upperBound(valueArray, value, first, last) {
   // this is just a binary search
   while (first < last) {
     const middle = (first + last) >>> 1;
@@ -84,7 +84,7 @@ function upperBound(valueArray, value, first, last) {
 
 // Inline performance optimization
 //
-function upperBoundIndirect(valueArray, indexArray, value, first, last) {
+export function upperBoundIndirect(valueArray, indexArray, value, first, last) {
   // this is just a binary search
   while (first < last) {
     const middle = (first + last) >>> 1;
@@ -96,11 +96,3 @@ function upperBoundIndirect(valueArray, indexArray, value, first, last) {
   }
   return first;
 }
-
-module.exports = {
-  fillRange,
-  lowerBound,
-  lowerBoundIndirect,
-  upperBound,
-  upperBoundIndirect
-};