Merge pull request #472 from rgarmsen2295/mm-1853

MM-1853 Prevents users from typing more than 4000 characters into any any post/comment

web/react/utils/utils.jsx

@@ -987,6 +987,58 @@ module.exports.isBrowserFirefox = function() {
     return navigator && navigator.userAgent && navigator.userAgent.toLowerCase().indexOf('firefox') > -1;
 };
 
+// Checks if browser is IE10 or IE11
+module.exports.isBrowserIE = function() {
+    if (window.navigator && window.navigator.userAgent) {
+        var ua = window.navigator.userAgent;
+
+        return ua.indexOf('Trident/7.0') > 0 || ua.indexOf('Trident/6.0') > 0;
+    }
+
+    return false;
+};
+
+module.exports.isBrowserEdge = function() {
+    return window.naviagtor && navigator.userAgent && navigator.userAgent.toLowerCase().indexOf('edge') > -1;
+};
+
+// Gets text length consistent with maxlength property of textarea html tag
+module.exports.getLengthOfTextInTextarea = function(messageText) {
+    // Need to get length with carriage returns counting as two characters to match textbox maxlength behavior
+    // unless ie10/ie11/edge which already do
+
+    var len = messageText.length;
+    if (!module.exports.isBrowserIE() && !module.exports.isBrowserEdge()) {
+        len = messageText.replace(/\r(?!\n)|\n(?!\r)/g, '--').length;
+    }
+
+    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('__');