在以下函数中，即使options函数调用链之前的console.log(options.destination)打印出来，我仍然遇到{.1}}在.then（）内被认为是未定义的问题正确。
storageObj但是如果我在.then（）中使用/**
* Returns a promise that resolves an object including the
* file destination if the requested file is downloaded successfully
* and rejects if there is an error whle downloading the file.
*
* @param {Object} storageObj GCS Storage object instance.
* @param {String} bucketName Name of the bucket to access in the GCS Storage object.
* @param {String} filePath Path of the file to access in the given bucketName.
* @param {String} destinationDir Name of the direcory to download the file to.
* @returns Promise
*/
function downloadGCSFileToDir(storageObj, bucketName, filePath, destinationDir) {
return new Promise((resolve, reject) => {
console.log("filePath is: " + filePath);
const filePathParts = filePath.split("/");
const destination = `${destinationDir}/${filePathParts[filePathParts.length - 1]}`;
const options = { "destination": destination };
console.log(options.destination);
storageObj
.bucket(bucketName)
.file(filePath)
.download(options)
.then(() => {
console.log(`gs://${bucketName}/${filePath} downloaded to ${options.destination}`);
resolve({ "destination": options.destination });
})
.catch(err => reject(new Error(`downloadGCSFileToDir failed: ${err}`)));
});
}
：
destination按预期打印。那是为什么？
答案 0 :(得分：2)
class AnotherClass {
[modifiers(?)] MyClass myObjects;
void initFunction( ... ) {
// some code
myObjects = new MyClass[] { ... };
}
MyClass accessFunction(int index) {
return myObjects[index];
}
}
在options内未定义; then是。原因是来自options.destination对象的download方法deletes the destination property。
options至于为什么这样做，你的猜测和我的一样好。