JSFiddle - React, Tailwind, and code Playground

HTML

<div id="textarea">
    <form name="query" class="form1" id="query" action="query.py" method="post">
        <textarea rows="2" name="message" id="message" class="message" placeholder="RM911 Chat" cols="26"></textarea>
        <input type="submit" id="submit" name="submit1" value="a"/>
    </form>
</div>

JavaScript

$(function(){
    function getCaret(el) {
        if (el.selectionStart) {
            return el.selectionStart;
        } else if (document.selection) {
            el.focus();
            
            var r = document.selection.createRange();
            if (r == null) {
                return 0;
            }
            
            var re = el.createTextRange(),
                rc = re.duplicate();
            re.moveToBookmark(r.getBookmark());
            rc.setEndPoint('EndToStart', re);
            
            return rc.text.length;
        }  
        return 0;
    }
    $("#message").keyup(function(e){
        if (e.keyCode == 13 && e.ctrlKey) {
            var content = $(this).val();
            var caret = getCaret(this);
            $(this).val(content.substring(0,caret)+
                        "\n"+content.substring(caret,content.length));
            e.stopPropagation();
        } else if (e.keyCode == 13){
            $("#submit").click();
        }
    });
});