How to upload multiple files using JavaScript SDK?

I am having a problem when I am trying to Loop through the files array. Here's my code

const files = req.files
const clientFolder = req.client_folder
const { dbxUser } = req;
const promises = []
for(const file of files){
	let args = {
		contents: file.buffer,
		path: `${clientFolder}/${file.originalname}`,
		mode: 'add',
		autorename: true,
		mute: false,
		strict_conflict: false
	}
	promises.push(dbxUser.filesUpload(args))
}
Promise.all(promises).then(i => {
	console.log(i)
	res.status(200).json({message: "Uploaded", status: i});
})

dbxUser.filesUpload(args) is an asynchronous function. So I am wondering How can I use this inside the loop.

In my above code I am expecting the function to store the promises in the array, But the promises array is blank in this case