Moved duplicate code into functions and added better handling of large paste text dumps

web/react/utils/utils.jsx

@@ -1032,6 +1032,30 @@ module.exports.getLengthOfTextInTextarea = function(messageText) {
     return len;
 };
 
+module.exports.checkMessageLengthError = function(message, currentError, newError) {
+    var updatedError = currentError;
+    var len = module.exports.getLengthOfTextInTextarea(message);
+
+    if (!currentError && len >= Constants.MAX_POST_LEN) {
+        updatedError = newError;
+    } else if (currentError === newError && len < Constants.MAX_POST_LEN) {
+        updatedError = '';
+    }
+
+    return updatedError;
+};
+
+// Necessary due to issues with textarea max length and pasting newlines
+module.exports.truncateText = function(message) {
+    var lengthDifference = module.exports.getLengthOfTextInTextarea(message) - message.length;
+
+    if (lengthDifference > 0) {
+        return message.substring(0, Constants.MAX_POST_LEN - lengthDifference);
+    }
+
+    return message.substring(0, Constants.MAX_POST_LEN);
+};
+
 // Used to get the id of the other user from a DM channel
 module.exports.getUserIdFromChannelName = function(channel) {
     var ids = channel.name.split('__');