Add escape button handler for form (reset)

static/library.js

@@ -11,6 +11,7 @@
       return {
         editing: false,
         saving: false,
+        trackForReset: {},
       }
     },
     computed: {
@@ -20,9 +21,17 @@
     },
     methods: {
       edit: function() {
+        if (this.editing) {
+          return;
+        }
+        this.trackForReset = Object.assign({}, this.track);
         this.saving = false;
         this.editing = true;
       },
+      cancel: function() {
+        this.track = Object.assign({}, this.trackForReset);
+        this.editing = false;
+      },
       save: function() {
         this.saving = true;
 
@@ -55,7 +64,7 @@
     template: `
       <div class="media-track" @click="edit()">
         <template v-if="editing">
-          <form method="patch" :action="patch_url">
+          <form method="patch" :action="patch_url" @keyup.27="cancel">
             <select v-model="track.tag" :disabled="saving">
               <option value=""></option>
               <option :class="{unused: tag.tag_count == 0}" v-for="tag in tags">