[рони]

Kurt_D_Cobain,
может так ...

function handleFiles(files) {
		initializeProgress(files.length)
        for (let i = 0; i < files.length; i++) {
            let div = document.createElement('div');
            div.className = "new";
            document.getElementById('gallery').appendChild(div)
        };
		files = [...files];
		files.forEach(uploadFile)
		files.forEach(previewFile)
		files.forEach(previewName)
		files.forEach(previewSize)
		files.forEach(removeFile);
        document.querySelectorAll("#gallery > div.new").forEach(div => div.classList.remove("new"))
	}

	function previewFile(file, i) {
		let reader = new FileReader()
		reader.readAsDataURL(file)
		reader.onloadend = function () {
			let img = document.createElement('img')
			img.src = reader.result
				document.querySelectorAll("#gallery > div.new")[i].appendChild(img)
		}
	}

	function previewName(file, i) {
			let reader = new FileReader()
			reader.readAsDataURL(file)
			reader.fileName = file.name
			reader.onloadend = function () {
				let title = document.createElement('span')
				title.innerHTML = reader.fileName
				document.querySelectorAll("#gallery > div.new")[i].appendChild(title)
		}
	}

	function previewSize(file, i) {
		let reader = new FileReader()
		reader.readAsDataURL(file)
		reader.fileSize = formatBytes(file.size)

		function formatBytes(bytes,decimals) {
			if(bytes == 0) return '0 Bytes';
			var k = 1024,
				dm = decimals <= 0 ? 0 : decimals || 2,
				sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'],
				i = Math.floor(Math.log(bytes) / Math.log(k));
			return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
		}

		reader.onloadend = function() {
			let size = document.createElement('div')
			size.innerHTML = reader.fileSize
			document.querySelectorAll("#gallery > div.new")[i].appendChild(size)
		}
	}

	function removeFile(file, i) {
		let reader = new FileReader()
		reader.readAsDataURL(file)
		reader.onloadend = function() {
			let remove = document.createElement('span')
			remove.setAttribute('id','RemoveFile')
			remove.innerHTML = 'x'
			document.querySelectorAll("#gallery > div.new")[i].appendChild(title)
		}
	}