JSFiddle - React, Tailwind, and code Playground

HTML

<textarea name="main_text" id="main_text" rows="10" cols="20">
    Start of text
    Press Enter somewhere here 
    Long long text .............
    End of text
</textarea>

JavaScript

$('textarea').keydown(function(ev){
if(ev.keyCode == 13){
var caretPos = document.getElementById("main_text").selectionStart;
var textAreaTxt = jQuery("#main_text").val();
var txtToAdd = "<br/>";
jQuery("#main_text").val(textAreaTxt.substring(0, caretPos) + txtToAdd + textAreaTxt.substring(caretPos) );
}
});