How to add javascript validation to choice field and check for a valid option?

Question

I have a choice field in a SharePoint 2010 List which has its first choice as Please Select. Now I want the functionality that we can validate if a user has selected any option apart from Please select i.e a user should not select "please select" as an option. It should show an error when that happens. It will be a great help if i could get the javascript.

Thanks in advance

Answer 1

You can check if the selected values text is equal to 'please select' and if so display an alert to the user telling them to select a value with the following code:

function validateForm() { 
    var elem = document.getElementById("yourElementID");
    var selectedText = elem.options[elem.selectedIndex].text;
    if (selectedText == "please select") {
        alert("Please select a value");
        return false;
    }
}

The return false; is important if you are attaching this code to a form submission for validation as it will prevent the form from being submitted.

You can attach this function to your forms onSubmit event by doing the following:

<form action="..." method="..." onsubmit="return validateForm()">

Answer 2

Its good solution explain in MitchS answer.but if you want to implement on ListItem Form like as NewForm, EditForm before Saving the item. than you should use PreSaveAction()

 function PreSaveAction()   
   {
     if($("select[title='My Choice'] option:selected").val() == '')
     {
        alert("Please select.")
        return false;
     }
    else
    {
    return true;
    }

  }

blow script find your choice dropdownlist control based on his title attribute.

Hops its helps!!!