Gracefully fail on window.dataLayer name conflict

segment-integrations · May 25, 2018 · a7cc8d5 · a7cc8d5
1 parent c65cea7
commit a7cc8d5
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/lib/index.js b/lib/index.js
@@ -30,6 +30,12 @@ var GTM = module.exports = integration('Google Tag Manager')
  */
 
 GTM.prototype.initialize = function() {
+  // If window.dataLayer already exists and isn't an array, fail gracefully.
+  if (window.dataLayer && !Array.isArray(window.dataLater)) {
+    console.error('window.dataLayer already exists - not running Segment<>GTM destination')
+    return;
+  }
+
   push({ 'gtm.start': Number(new Date()), event: 'gtm.js' });
 
   if (this.options.environment.length) {