How to set validation errors in ModelState to corresponding html element title

I have following code in Razor view:

@using (Html.BeginForm("Edit", "Person", FormMethod.Post, new { ... }))
{
    ...
    <div class="field">
        @Html.LabelFor(m => m.FirstName, "Firstname")
        @Html.TextBoxFor(m => m.FirstName</div>)
        @Html.ValidationMessageFor(m => m.FirstName)
    </div>
    <div class="field">
        @Html.LabelFor(m => m.LastName, "LastName")
        @Html.TextBoxFor(m => m.LastName</div>)
        @Html.ValidationMessageFor(m => m.LastName)
    </div>
    <div class="field">
        @Html.LabelFor(m => m.PhoneNumber, "PhoneNumber")
        @Html.TextBoxFor(m => m.PhoneNumber)
        @Html.ValidationMessageFor(m => m.PhoneNumber)
    </div>
    ...
}

When form gets posted, controller does validation and populates ModelState (dictionary) with error messages for those fields that are required but missing. These error messages are shown in a separate span next to the text boxes.

Now, instead of showing the error message as a separate span-element, I would rather like to set it as a title for the corresponding textbox (so that it shows as a tooltip).

I figure I will have to set the title of the textbox after POST returns and loop through all validation errors, so something like this:

foreach (KeyValuePair<TKey, TValue> pair in ViewState.ModelState)
{
    var k = pair.Key;
    var v = pair.Value;

    // Iterate over all errors and set the error
    // message as title for textbox
    foreach (var error in pair.Value.Errors)
    {
        // Ignore some keys...
        if(pair.Key != "ErrorMessageSummary")
        {
            // Find the element that was missing value and set title:
            $(@Html.IdFor(m => pair.Key)).prop({
                title: error.ErrorMessage,
            });
        }
    }
}

There is a JavaScript function that gets called when user clicks 'save'-button:

$('#save').on('click', function (e) {
    submitForm('@Url.Action("Save", "Person")', '@formId', '@waitMessage', '@successMessage');
    return false;
});

Being a novice in JavaScript and Razor, I can't quote figure this out.

Questions

• How do I do this?
• Where do I do this?

Thanks!