Fix ESLint errors

frontend/src/fileSender.js

@@ -13,7 +13,7 @@ class FileSender extends EventEmitter {
       if (!fileId || !token) {
         return reject();
       }
-      let xhr = new XMLHttpRequest();
+      const xhr = new XMLHttpRequest();
       xhr.open('post', '/delete/' + fileId, true);
       xhr.setRequestHeader('Content-Type', 'application/json');
 
@@ -51,55 +51,55 @@ class FileSender extends EventEmitter {
         };
       })
     ])
-    .then(([secretKey, plaintext]) => {
-      return Promise.all([
-        window.crypto.subtle.encrypt(
-          {
-            name: 'AES-CBC',
-            iv: this.iv
-          },
-          secretKey,
-          plaintext
-        ),
-        window.crypto.subtle.exportKey('jwk', secretKey)
-      ]);
-    })
-    .then(([encrypted, keydata]) => {
-      return new Promise((resolve, reject) => {
-        let file = this.file;
-        let fileId = ivToStr(this.iv);
-        let dataView = new DataView(encrypted);
-        let blob = new Blob([dataView], { type: file.type });
-        let fd = new FormData();
-        fd.append('fname', file.name);
-        fd.append('data', blob, file.name);
+      .then(([secretKey, plaintext]) => {
+        return Promise.all([
+          window.crypto.subtle.encrypt(
+            {
+              name: 'AES-CBC',
+              iv: this.iv
+            },
+            secretKey,
+            plaintext
+          ),
+          window.crypto.subtle.exportKey('jwk', secretKey)
+        ]);
+      })
+      .then(([encrypted, keydata]) => {
+        return new Promise((resolve, reject) => {
+          const file = this.file;
+          const fileId = ivToStr(this.iv);
+          const dataView = new DataView(encrypted);
+          const blob = new Blob([dataView], { type: file.type });
+          const fd = new FormData();
+          fd.append('fname', file.name);
+          fd.append('data', blob, file.name);
 
-        let xhr = new XMLHttpRequest();
+          const xhr = new XMLHttpRequest();
 
-        xhr.upload.addEventListener('progress', e => {
-          if (e.lengthComputable) {
-            let percentComplete = Math.floor(e.loaded / e.total * 100);
-            this.emit('progress', percentComplete);
-          }
+          xhr.upload.addEventListener('progress', e => {
+            if (e.lengthComputable) {
+              const percentComplete = Math.floor(e.loaded / e.total * 100);
+              this.emit('progress', percentComplete);
+            }
+          });
+
+          xhr.onreadystatechange = () => {
+            if (xhr.readyState === XMLHttpRequest.DONE) {
+              // uuid field and url field
+              const responseObj = JSON.parse(xhr.responseText);
+              resolve({
+                url: responseObj.url,
+                fileId: fileId,
+                secretKey: keydata.k,
+                deleteToken: responseObj.uuid
+              });
+            }
+          };
+
+          xhr.open('post', '/upload/' + fileId, true);
+          xhr.send(fd);
         });
-
-        xhr.onreadystatechange = () => {
-          if (xhr.readyState == XMLHttpRequest.DONE) {
-            // uuid field and url field
-            let responseObj = JSON.parse(xhr.responseText);
-            resolve({
-              url: responseObj.url,
-              fileId: fileId,
-              secretKey: keydata.k,
-              deleteToken: responseObj.uuid
-            });
-          }
-        };
-
-        xhr.open('post', '/upload/' + fileId, true);
-        xhr.send(fd);
       });
-    });
   }
 }