ConditionalJquery

HTML

Text <input type="text">
<button>Click Me</button>



<input id ="sal">

JavaScript

$("button").on("click",function(){
    	var input = $("input[type='text']");
      
      
      var button = 
      
	    if(!input.val()){
  	        input.css("border","2px solid red");
        }
    });