How to impose a required textbox in javascript

Question

I have a problem with my chat. Indeed, I have a text input with the required value. When I click on Send, it returns empty instead of stopped sending... Can you help me please ?

<script>
    $("#submitmsg").click(function() {
        var clientmsg = $("#usermsg").val();
        $.post("chat-post.php", {
            text: clientmsg
        }); 

$("#usermsg").attr('required', true);

        loadLog;
        return false;
    });
</script>

Answer 1

you could validate the input string like this if(clientmsg.trim()) .Better add the required=true in your html code

 <input type='text' required="true">

And use with trim() they will remove the unwanted space from string

<script>
    $("#submitmsg").click(function() {
        var clientmsg = $("#usermsg").val();
        if(clientmsg.trim()){
        $.post("chat-post.php", {
            text: clientmsg
        }); 
        loadLog;
        }
        return false;
    });
</script>