Converted create_merge_request_dropdown to axios

app/assets/javascripts/create_merge_request_dropdown.js

 /* eslint-disable no-new */
 import _ from 'underscore';
+import axios from './lib/utils/axios_utils';
 import Flash from './flash';
 import DropLab from './droplab/drop_lab';
 import ISetter from './droplab/plugins/input_setter';
@@ -74,13 +75,10 @@ export default class CreateMergeRequestDropdown {
   }
 
   checkAbilityToCreateBranch() {
-    return $.ajax({
-      type: 'GET',
-      dataType: 'json',
-      url: this.canCreatePath,
-      beforeSend: () => this.setUnavailableButtonState(),
-    })
-    .done((data) => {
+    this.setUnavailableButtonState();
+
+    axios.get(this.canCreatePath)
+      .then(({ data }) => {
         this.setUnavailableButtonState(false);
 
         if (data.can_create_branch) {
@@ -95,39 +93,34 @@ export default class CreateMergeRequestDropdown {
         } else if (data.has_related_branch) {
           this.hide();
         }
-    }).fail(() => {
+      })
+      .catch(() => {
         this.unavailable();
         this.disable();
-      new Flash('Failed to check if a new branch can be created.');
+        Flash('Failed to check if a new branch can be created.');
       });
   }
 
   createBranch() {
-    return $.ajax({
-      method: 'POST',
-      dataType: 'json',
-      url: this.createBranchPath,
-      beforeSend: () => (this.isCreatingBranch = true),
-    })
-    .done((data) => {
+    this.isCreatingBranch = true;
+
+    return axios.post(this.createBranchPath)
+      .then(({ data }) => {
         this.branchCreated = true;
         window.location.href = data.url;
       })
-    .fail(() => new Flash('Failed to create a branch for this issue. Please try again.'));
+      .catch(() => Flash('Failed to create a branch for this issue. Please try again.'));
   }
 
   createMergeRequest() {
-    return $.ajax({
-      method: 'POST',
-      dataType: 'json',
-      url: this.createMrPath,
-      beforeSend: () => (this.isCreatingMergeRequest = true),
-    })
-    .done((data) => {
+    this.isCreatingMergeRequest = true;
+
+    return axios.post(this.createMrPath)
+      .then(({ data }) => {
         this.mergeRequestCreated = true;
         window.location.href = data.url;
       })
-    .fail(() => new Flash('Failed to create Merge Request. Please try again.'));
+      .catch(() => Flash('Failed to create Merge Request. Please try again.'));
   }
 
   disable() {
@@ -200,18 +193,8 @@ export default class CreateMergeRequestDropdown {
   getRef(ref, target = 'all') {
     if (!ref) return false;
 
-    return $.ajax({
-      method: 'GET',
-      dataType: 'json',
-      url: this.refsPath + ref,
-      beforeSend: () => {
-        this.isGettingRef = true;
-      },
-    })
-    .always(() => {
-      this.isGettingRef = false;
-    })
-    .done((data) => {
+    return axios.get(this.refsPath + ref)
+      .then(({ data }) => {
         const branches = data[Object.keys(data)[0]];
         const tags = data[Object.keys(data)[1]];
         let result;
@@ -224,13 +207,17 @@ export default class CreateMergeRequestDropdown {
           this.suggestedRef = result;
         }
 
+        this.isGettingRef = false;
+
         return this.updateInputState(target, ref, result);
       })
-    .fail(() => {
+      .catch(() => {
         this.unavailable();
         this.disable();
         new Flash('Failed to get ref.');
 
+        this.isGettingRef = false;
+
         return false;
       });
   }
@@ -332,12 +319,12 @@ export default class CreateMergeRequestDropdown {
       xhr = this.createBranch();
     }
 
-    xhr.fail(() => {
+    xhr.catch(() => {
       this.isCreatingMergeRequest = false;
       this.isCreatingBranch = false;
-    });
 
-    xhr.always(() => this.enable());
+      this.enable();
+    });
 
     this.disable();
   }