Merge pull request #45 from Esri/feat/script-onerror

handle script load errors

CHANGELOG.md

@@ -2,6 +2,11 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
+## [Unreleased]
+
+### Added
+- handle script load errors
+
 ## [1.3.0]
 
 ### Added

src/esri-loader.ts

@@ -33,6 +33,7 @@ export function isLoaded() {
 
 // load the ArcGIS API on the page
 export function bootstrap(callback?: (error: Error, dojoRequire?: any) => void, options: IBootstrapOptions = {}) {
+  // default options
   if (!options.url) {
     options.url = 'https://js.arcgis.com/4.5/';
   }
@@ -72,6 +73,17 @@ export function bootstrap(callback?: (error: Error, dojoRequire?: any) => void,
     }
   };
 
+  // handle any script loading errors
+  const onScriptError = (e) => {
+    if (callback) {
+      // pass the error to the callback
+      callback(e.error || new Error(`There was an error attempting to load ${script.src}`));
+    }
+    // remove this event listener
+    script.removeEventListener('error', onScriptError, false);
+  };
+  script.addEventListener('error', onScriptError, false);
+
   // load the script
   document.body.appendChild(script);
 }

test/esri-loader.spec.js

@@ -88,20 +88,19 @@ describe('esri-loader', function () {
       var context = {
         bootstrapCallback: function () {}
       };
-      describe('w/ a callback', function () {
-        beforeAll(function () {
-          spyOn(document.body, 'appendChild').and.callFake(function (el) {
-            // hold onto script element for assertions below
-            scriptEl = el;
-            // call the onload callback
-            el.onload();
-          });
-          spyOn(document, 'querySelector').and.callFake(function() {
-            console.log('querySelector', scriptEl);
-            return scriptEl;
-          });
-          spyOn(context, 'bootstrapCallback');
+      beforeAll(function () {
+        spyOn(document.body, 'appendChild').and.callFake(function (el) {
+          // hold onto script element for assertions below
+          scriptEl = el;
+          // call the onload callback
+          el.onload();
         });
+        spyOn(document, 'querySelector').and.callFake(function() {
+          return scriptEl;
+        });
+        spyOn(context, 'bootstrapCallback');
+      });
+      describe('w/ a callback', function () {
         it('should pass an error to the callback', function () {
           esriLoader.bootstrap(context.bootstrapCallback, {
             url: 'https://js.arcgis.com/3.20'
@@ -124,6 +123,23 @@ describe('esri-loader', function () {
         });
       });
     });
+    describe('when loading an invalid url', function () {
+      it('should pass an error to the callback', function (done) {
+        esriLoader.bootstrap((err) => {
+          expect(err.message.indexOf('There was an error attempting to load')).toEqual(0);
+          done();
+        }, {
+          url: 'not a valid url'
+        });
+      });
+      afterAll(function () {
+        // remove script tag
+        const script = document.querySelector('script[data-esri-loader]');
+        if (script) {
+          script.parentElement.removeChild(script);
+        }
+      });
+    });
   });
 
   describe('when loading modules', function () {