Widget: fix running different versions of Vue on the same page

src/pretix/static/pretixpresale/js/widget/widget.js

@@ -11,7 +11,6 @@ window.PretixWidget = {
 };
 
 var Vue = module.exports;
-Vue.component('resize-observer', VueResize.ResizeObserver)
 
 var strings = {
     'quantity': django.pgettext('widget', 'Quantity'),
@@ -736,9 +735,6 @@ var shared_methods = {
             window.open(redirect_url);
         }
     },
-    handleResize: function () {
-        this.mobile = this.$refs.wrapper.clientWidth <= 800;
-    }
 };
 
 var shared_widget_data = function () {
@@ -1493,7 +1489,6 @@ Vue.component('pretix-widget-event-week-calendar', {
 Vue.component('pretix-widget', {
     template: ('<div class="pretix-widget-wrapper" ref="wrapper">'
         + '<div :class="classObject">'
-        + '<resize-observer @notify="handleResize" />'
         + shared_loading_fragment
         + '<div class="pretix-widget-error-message" v-if="$root.error && $root.view !== \'event\'">{{ $root.error }}</div>'
         + '<div class="pretix-widget-error-action" v-if="$root.error && $root.connection_error"><a :href="$root.newTabTarget" class="pretix-widget-button" target="_blank">'
@@ -1513,7 +1508,22 @@ Vue.component('pretix-widget', {
     data: shared_widget_data,
     methods: shared_methods,
     mounted: function () {
-        this.mobile = this.$refs.wrapper.clientWidth <= 600;
+        var thisObj = this;
+        if ("ResizeObserver" in window) {
+            var resizeObserver = new ResizeObserver(function(entries) {
+                thisObj.mobile = entries[0].contentRect.width <= 800;
+            });
+            resizeObserver.observe(this.$refs.wrapper);
+        } else {
+            this.mobile = this.$refs.wrapper.clientWidth <= 800;
+            var debounce;
+            window.addEventListener("resize", function() {
+                if (debounce) clearTimeout(debounce);
+                debounce = setTimeout(function () {
+                    thisObj.mobile = thisObj.$refs.wrapper.clientWidth <= 800;
+                }, 100);
+            });
+        }
     },
     computed: {
         classObject: function () {

src/pretix/static/pretixpresale/scss/widget.scss

@@ -1000,6 +1000,3 @@
     }
   }
 }
-
-// https://github.com/Akryum/vue-resize/blob/master/dist/vue-resize.css
-.resize-observer[data-v-b329ee4c]{position:absolute;top:0;left:0;z-index:-1;width:100%;height:100%;border:none;background-color:transparent;pointer-events:none;display:block;overflow:hidden;opacity:0}.resize-observer[data-v-b329ee4c] object{display:block;position:absolute;top:0;left:0;height:100%;width:100%;overflow:hidden;pointer-events:none;z-index:-1}