gistfile1.js

// You are doomed if you use anchors. 
// Page_IsValid is always true as its validators are never triggered. This only works on a form submit.

// I have come up with a solution that works well using anchors and using the client side asp.net validation functions with web forms:
// Since the anchors can contain many general things, there a few anchors you would want to exclude, including those which open modals or add / remove rows when posting data.


// We know any btn-cancel could potentially close a modal, we ignore these
// we know any void(0) functions are going to open up a modal, or they will add/remove rows, we ignore these
// We know exports of results could be downloaded multiple times, we ignore these
var excludes = $('a[title*="Export"], a.btn-cancel, a[href="javascript:void(0)"]');

// Include any anchors that could will endure a post back (__DoPostBack, PostBackWithOptions)
var includes = $('a.button[href*="PostBack"], a.button');  

$(includes).not(excludes).click(function (e) 
{
    // the page is valid after controls validate the inputs in the form
    if (Page_ClientValidate()) 
    { 
        // disable the anchor, give it a disabled class, be careful removing the href or javascript if the function has not already been called.
        $(this)
            .attr('disabled', 'disabled')
            .attr('title', 'Please wait...')
            .click(function (event) { event.preventDefault(); }); // stop any further click events from triggering again
  
       // optional features and things to do
       var icon = $(this).find('i'); // font awesome icon to replace any current icon with a loading icon
  
        // Acknowledge that the page is loading / in progress.
        if (icon)
        {
            $(icon).removeClass().addClass('fa fa-spinner fa-spin');
        }
    }
    else
    {
       e.preventDefault(); // Page not valid, do not trigger post back.
    }
});