当两个字段为空javascript/jquery时如何显示错误消息？

Question

How to display error messgae using javascript or jquery only when both the feilds are empty. For example a user can either enter Zipcode or select a state from dropdown. If the user doesnot select any one of those then the error should be displayed.

Answer 1

You can get the value of the elements by document.getElementById("id").value

 function Validate() { var zip = document.getElementById("zip").value; var state = document.getElementById("state").value; if(zip == "" && state == 0) { document.getElementById("error").innerHTML = "Error message"; } else { document.getElementById("error").innerHTML = ""; } }

 <input type="text" id="zip"> <select id="state"> <option value="0">Select a state</option> <option value="State 1">State 1</option> <option value="State 2">State 2</option> <option value="State 3">State 3</option> <option value="State 4">State 4</option> </select> <p id="error"></p> <button onclick="Validate()">Submit</button>

Note : You can disable an element when the other is selected using document.getElementById("id").disabled = true;