Remove markdown on toolbar click

packages/rocketchat-ui-message/client/messageBox.js

@@ -35,6 +35,37 @@ function applyMd(e, t) {
 		}, 100);
 	}
 	box.focus();
+
+	// removes markdown if selected text in inside the same clicked markdown
+	if (selectionStart !== selectionEnd) {
+		const startPattern = this.pattern.substr(0, this.pattern.indexOf('{{text}}'));
+		const startPatternFound = [...startPattern].reverse().every((char, index) => {
+			return box.value.substr(selectionStart - index - 1, 1) === char;
+		});
+
+		if (startPatternFound) {
+			const endPattern = this.pattern.substr(this.pattern.indexOf('{{text}}') + '{{text}}'.length);
+			const endPatternFound = [...endPattern].every((char, index) => {
+				return box.value.substr(selectionEnd + index, 1) === char;
+			});
+
+			if (endPatternFound) {
+				box.selectionStart = selectionStart - startPattern.length;
+				box.selectionEnd = selectionEnd + endPattern.length;
+
+				if (document.execCommand) {
+					document.execCommand('insertText', false, selectedText);
+				} else {
+					box.value = initText.substr(0, initText.length - startPattern.length) + selectedText + finalText.substr(endPattern.length);
+				}
+				box.selectionStart = selectionStart - startPattern.length;
+				box.selectionEnd = box.selectionStart + selectedText.length;
+				$(box).change();
+				return;
+			}
+		}
+	}
+
 	/*
 		get text
 		apply pattern