异步/等待上传任务

我如何等待 uploadTask 以便在将下载 url 和文档插入到 firestore 之前先上传图像/文件并跟踪其进度，

以下代码是我的示例 Vue 项目。它工作正常，但请参阅if (portraitFile)，必须满足我必须上传图片的条件，如果我不想上传图片怎么办？

它必须移出该条件if，但它将在文件完成并检索下载 URL 之前异步执行。

目标：将 firestore add() 移到 uploadTask 的完成回调/参数之外。

    async commitCharacter() {
      try {
        let character = this.character;
        let portraitFile = this.portraitFile;

        if (portraitFile) {
          const uploadTask = storageRef
            .child(`characters/${character.id}/portrait.png`)
            .put(portraitFile, { contentType: "image/png" });

          await uploadTask.on(
            "state_changed",
            snapshot => {
              this.portraitUploadProgress =
                (snapshot.bytesTransferred / snapshot.totalBytes) * 100;
            },
            null,
            async () => {
              character.portraitUrl = await storageRef
                .child(`characters/${character.id}/portrait.png`)
                .getDownloadURL();

              if (character.id) {
              await db
                .collection("characters")
                .doc(character.id)
                .update(character);
              } else {
                character.id = (await 
                db.collection("characters").add(character)).id;
              }

              $("#manageCharacter").modal("hide");
            }
          );
        }
      }

你可以把你的uploadTask承诺：

async function uploadTaskPromise() {
  return new Promise(function(resolve, reject) {
    const storageRef = storage.ref(YOUR_STORAGE_PATH)
    const uploadTask = storageRef.put(YOUR_FILE_OR_BLOB)
    uploadTask.on('state_changed',
      function(snapshot) {
        var progress = (snapshot.bytesTransferred / snapshot.totalBytes) * 100
        console.log('Upload is ' + progress + '% done')
      },
      function error(err) {
        console.log('error', err)
        reject()
      },
      function complete() {
        uploadTask.snapshot.ref.getDownloadURL().then(function(downloadURL) {
          resolve(downloadURL)
        })
      }
    )
  })
}

然后像这样使用它：

const storageUrl = await uploadTaskPromise()
console.log(storageUrl) // do whatever you want with the URL...