If file is not an image / audio / video or larger then 10 mb don't try and show a preview

packages/rocketchat-ui/client/lib/fileUpload.coffee

@@ -5,6 +5,31 @@ readAsDataURL = (file, callback) ->
 
 	reader.readAsDataURL file
 
+getUploadPreview = (file, callback) ->
+	if file.file.type.indexOf('audio') > -1 or file.file.type.indexOf('video') > -1 or file.file.type.indexOf('image') > -1
+		file.type = file.file.type.split('/')[0]
+
+		readAsDataURL file.file, (content) ->
+			callback(file, content)
+	else
+		callback(file, null)
+
+formatBytes = (bytes, decimals) ->
+  if bytes == 0
+    return '0 Bytes'
+  k = 1000
+  dm = decimals + 1 or 3
+  sizes = [
+    'Bytes'
+    'KB'
+    'MB'
+    'GB'
+    'TB'
+    'PB'
+  ]
+  i = Math.floor(Math.log(bytes) / Math.log(k))
+  parseFloat((bytes / k ** i).toFixed(dm)) + ' ' + sizes[i]
+
 readAsArrayBuffer = (file, callback) ->
 	reader = new FileReader()
 	reader.onload = (ev) ->
@@ -23,29 +48,29 @@ readAsArrayBuffer = (file, callback) ->
 			swal.close()
 			return
 
-		readAsDataURL file.file, (fileContent) ->
-			if not RocketChat.fileUploadIsValidContentType file.file.type
-				swal
-					title: t('FileUpload_MediaType_NotAccepted')
-					text: file.file.type || "*.#{s.strRightBack(file.file.name, '.')}"
-					type: 'error'
-					timer: 3000
-				return
-
-			if file.file.size is 0
-				swal
-					title: t('FileUpload_File_Empty')
-					type: 'error'
-					timer: 1000
-				return
+		if not RocketChat.fileUploadIsValidContentType file.file.type
+			swal
+				title: t('FileUpload_MediaType_NotAccepted')
+				text: file.file.type || "*.#{s.strRightBack(file.file.name, '.')}"
+				type: 'error'
+				timer: 3000
+			return
+
+		if file.file.size is 0
+			swal
+				title: t('FileUpload_File_Empty')
+				type: 'error'
+				timer: 1000
+			return
 
+		getUploadPreview file, (file, preview) ->
 			text = ''
 
 			if file.type is 'audio'
 				text = """
 					<div class='upload-preview'>
 						<audio  style="width: 100%;" controls="controls">
-							<source src="#{fileContent}" type="audio/wav">
+							<source src="#{preview}" type="audio/wav">
 							Your browser does not support the audio element.
 						</audio>
 					</div>
@@ -58,7 +83,7 @@ readAsArrayBuffer = (file, callback) ->
 				text = """
 					<div class='upload-preview'>
 						<video  style="width: 100%;" controls="controls">
-							<source src="#{fileContent}" type="video/webm">
+							<source src="#{preview}" type="video/webm">
 							Your browser does not support the video element.
 						</video>
 					</div>
@@ -67,10 +92,22 @@ readAsArrayBuffer = (file, callback) ->
 						<input id='file-description' style='display: inherit;' value='' placeholder='#{t("Upload_file_description")}'>
 					</div>
 				"""
+			else if file.type is 'image'
+				text = """
+					<div class='upload-preview'>
+						<div class='upload-preview-file' style='background-image: url(#{preview})'></div>
+					</div>
+					<div class='upload-preview-title'>
+						<input id='file-name' style='display: inherit;' value='#{Handlebars._escape(file.name)}' placeholder='#{t("Upload_file_name")}'>
+						<input id='file-description' style='display: inherit;' value='' placeholder='#{t("Upload_file_description")}'>
+					</div>
+				"""
 			else
+				fileSize = formatBytes(file.file.size)
+
 				text = """
 					<div class='upload-preview'>
-						<div class='upload-preview-file' style='background-image: url(#{fileContent})'></div>
+						<div>#{Handlebars._escape(file.name)} - #{fileSize}</div>
 					</div>
 					<div class='upload-preview-title'>
 						<input id='file-name' style='display: inherit;' value='#{Handlebars._escape(file.name)}' placeholder='#{t("Upload_file_name")}'>