Firebase 给出错误：无法读取未定义的属性“ref”

Question

我想在 firebase 存储中上传照片，一旦上传了要在控制台上打印的下载 URL。 照片完美上传，没有任何问题，但在控制台而不是 downloadURL 中，打印 undefined 并引发错误，指出“TypeError：无法读取未定义的属性 'ref'”。

const file = $('#exampleInputFile').get(0).files[0]; // getting file to be uploaded 
const name = (+new Date() + '-' + file.name); // creating filename with timestamp
const task = ref.child(name).put(file, {contentType: file.type});  //setting file 

task.then( (snapshot) =>  console.log (snapshot.downloadURL))
.then(downloadURL => {
console.log(`Successfully uploaded file and got download link -
${downloadURL}`);
// once done trying to get downloadURL against this upload

})

.catch(error => {
 // Use to signal error if something goes wrong.
 console.log(`Failed to upload file and get link - ${error}`);
});
//or throw and error in console

Answer 1

save() {
    this.storageref.child(this.file.name).put(this.file).then(snapshot => {
        let image = snapshot.metadata.downloadURLs[0];
            consol.log(image);
        });
    }