JSFiddle - React, Tailwind, and code Playground

HTML

<input id="Textbox1" type="text"/>
<input type="button" value="Check" onclick="Check();">

JavaScript

function Check(){
val = document.getElementById("Textbox1").value;
val = val.split(',');
    var is_Error = false;
    var ErrrMsg = "All entries must be seven (7) characters in lenght.  Please correct the following entries:\n";
for(var i=0;i<val.length;i++){    
    if((val[i].length !=7) && (val[i].length !=0)){
        ErrrMsg += val[i] +  ",";
        is_Error = true;
    }    
}
    if(is_Error == true){
     alert(ErrrMsg.substring(0,(ErrrMsg.length - 1)));
        return false;
    }
return true; 
}