From 528ea86cbf587f8871282a28bd6f637772d69f1c Mon Sep 17 00:00:00 2001
From: Rachel Fenichel <fenichel@google.com>
Date: Tue, 3 Jan 2017 14:58:05 -0800
Subject: [PATCH] Check if the text has changed before firing an event

---
 core/field_textinput.js | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/core/field_textinput.js b/core/field_textinput.js
index 3d224c031..5c6e66215 100644
--- a/core/field_textinput.js
+++ b/core/field_textinput.js
@@ -99,6 +99,15 @@ Blockly.FieldTextInput.prototype.setValue = function(newValue) {
  * @param {*} newText New text.
  */
 Blockly.FieldTextInput.prototype.setText = function(newText) {
+  if (newText === null) {
+    // No change if null.
+    return;
+  }
+  newText = String(newText);
+  if (newText === this.text_) {
+    // No change.
+    return;
+  }
   if (this.sourceBlock_ && Blockly.Events.isEnabled()) {
     Blockly.Events.fire(new Blockly.Events.Change(
         this.sourceBlock_, 'field', this.name, this.text_, newText));