diff --git a/static/js/tracker/tracker-util.js b/static/js/tracker/tracker-util.js
new file mode 100644
index 0000000..040f8c1
--- /dev/null
+++ b/static/js/tracker/tracker-util.js
@@ -0,0 +1,166 @@
+/* Copyright 2016 The Chromium Authors. All Rights Reserved.
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file or at
+ * https://developers.google.com/open-source/licenses/bsd
+ */
+
+/**
+ * This file contains JS utilities used by other JS files in Monorail.
+ */
+
+
+/**
+ * Add an indexOf method to all arrays, if this brower's JS implementation
+ * does not already have it.
+ * @param {Object} item The item to find
+ * @return {number} The index of the given item, or -1 if not found.
+ */
+if (Array.prototype.indexOf == undefined) {
+  Array.prototype.indexOf = function(item) {
+    for (let i = 0; i < this.length; ++i) {
+      if (this[i] == item) return i;
+    }
+    return -1;
+  };
+}
+
+
+/**
+ * This function works around a FF HTML layout problem.  The table
+ * width is somehow rendered at 100% when the table contains a
+ * display:none element, later, when that element is displayed, the
+ * table renders at the correct width.  The work-around is to have the
+ * element initiallye displayed so that the table renders properly,
+ * but then immediately hide the element until it is needed.
+ *
+ * TODO(jrobbins): Find HTML markup that FF can render more
+ * consistently.  After that, I can remove this hack.
+ */
+function TKR_forceProperTableWidth() {
+  let e = $('confirmarea');
+  if (e) e.style.display='none';
+}
+
+
+function TKR_parseIssueRef(issueRef) {
+  issueRef = issueRef.trim();
+  if (!issueRef) {
+    return null;
+  }
+
+  let projectName = window.CS_env.projectName;
+  let localId = issueRef;
+  if (issueRef.includes(':')) {
+    const parts = issueRef.split(':', 2);
+    projectName = parts[0];
+    localId = parts[1];
+  }
+
+  return {
+    project_name: projectName,
+    local_id: localId};
+}
+
+
+function _buildFieldsForIssueDelta(issueDelta, valuesByName) {
+  issueDelta.field_vals_add = [];
+  issueDelta.field_vals_remove = [];
+  issueDelta.fields_clear = [];
+
+  valuesByName.forEach((values, key, map) => {
+    if (key.startsWith('op_custom_') && values == 'clear') {
+      const field_id = key.substring('op_custom_'.length);
+      issueDelta.fields_clear.push({field_id: field_id});
+    } else if (key.startsWith('custom_')) {
+      const field_id = key.substring('custom_'.length);
+      values = values.filter(Boolean);
+      if (valuesByName.get('op_' + key) === 'remove') {
+        values.forEach((value) => {
+          issueDelta.field_vals_remove.push({
+            field_ref: {field_id: field_id},
+            value: value});
+        });
+      } else {
+        values.forEach((value) => {
+          issueDelta.field_vals_add.push({
+            field_ref: {field_id: field_id},
+            value: value});
+        });
+      }
+    }
+  });
+}
+
+
+function _classifyPlusMinusItems(values) {
+  let result = {
+    add: [],
+    remove: []};
+  values = new Set(values);
+  values.forEach((value) => {
+    if (!value.startsWith('-') && value) {
+      result.add.push(value);
+    } else if (value.startsWith('-') && value.substring(1)) {
+      result.remove.push(value);
+    }
+  });
+  return result;
+}
+
+
+function TKR_buildIssueDelta(valuesByName) {
+  let issueDelta = {};
+
+  if (valuesByName.has('status')) {
+    issueDelta.status = valuesByName.get('status')[0];
+  }
+  if (valuesByName.has('owner')) {
+    issueDelta.owner_ref = {
+      display_name: valuesByName.get('owner')[0].trim().toLowerCase()};
+  }
+  if (valuesByName.has('cc')) {
+    const cc_usernames = _classifyPlusMinusItems(
+      valuesByName.get('cc')[0].toLowerCase().split(/[,;\s]+/));
+    issueDelta.cc_refs_add = cc_usernames.add.map(
+      (email) => ({display_name: email}));
+    issueDelta.cc_refs_remove = cc_usernames.remove.map(
+      (email) => ({display_name: email}));
+  }
+  if (valuesByName.has('components')) {
+    const components = _classifyPlusMinusItems(
+      valuesByName.get('components')[0].split(/[,;\s]/));
+    issueDelta.comp_refs_add = components.add.map(
+      (path) => ({path: path}));
+    issueDelta.comp_refs_remove = components.remove.map(
+      (path) => ({path: path}));
+  }
+  if (valuesByName.has('label')) {
+    const labels = _classifyPlusMinusItems(valuesByName.get('label'));
+    issueDelta.label_refs_add = labels.add.map(
+      (label) => ({label: label}));
+    issueDelta.label_refs_remove = labels.remove.map(
+      (label) => ({label: label}));
+  }
+  if (valuesByName.has('blocked_on')) {
+    const blockedOn = _classifyPlusMinusItems(valuesByName.get('blocked_on'));
+    issueDelta.blocked_on_refs_add = blockedOn.add.map(TKR_parseIssueRef);
+    issueDelta.blocked_on_refs_add = blockedOn.remove.map(TKR_parseIssueRef);
+  }
+  if (valuesByName.has('blocking')) {
+    const blocking = _classifyPlusMinusItems(valuesByName.get('blocking'));
+    issueDelta.blocking_refs_add = blocking.add.map(TKR_parseIssueRef);
+    issueDelta.blocking_refs_add = blocking.remove.map(TKR_parseIssueRef);
+  }
+  if (valuesByName.has('merge_into')) {
+    issueDelta.merged_into_ref = TKR_parseIssueRef(
+      valuesByName.get('merge_into')[0]);
+  }
+  if (valuesByName.has('summary')) {
+    issueDelta.summary = valuesByName.get('summary')[0];
+  }
+
+  _buildFieldsForIssueDelta(issueDelta, valuesByName);
+
+  return issueDelta;
+}