How to display page loading indicator using spin.js

Question

I am learning how to use Spin.js so that a loading indicator (the spinner) can be shown while the web page is loading.

I got it working but I am not sure whether I am calling the spin/stop in the proper page lifecycle. Is it possible to show the spinner before $(window).ready ?

<script type="text/javascript">
var spinner;

$(window).ready(function loadingAnimation() {
    var opts = {
      lines: 13, // The number of lines to draw
      length: 7, // The length of each line
      width: 4, // The line thickness
      radius: 10, // The radius of the inner circle
      corners: 1, // Corner roundness (0..1)
      rotate: 0, // The rotation offset
      color: '#000', // #rgb or #rrggbb
      speed: 1, // Rounds per second
      trail: 60, // Afterglow percentage
      shadow: false, // Whether to render a shadow
      hwaccel: false, // Whether to use hardware acceleration
      className: 'spinner', // The CSS class to assign to the spinner
      zIndex: 2e9, // The z-index (defaults to 2000000000)
      top: 'auto', // Top position relative to parent in px
      left: 'auto' // Left position relative to parent in px
    };
    var target = $("body")[0];
    spinner = new Spinner(opts).spin(target);
});

window.onload = function() {
    spinner.stop();
};

For the working example, please see http://sgratrace.appspot.com/industry.html

Solution

I created an object to control the spinning:

Rats.UI.LoadAnimation = {
    "start" : function(){
        var opts = {
            lines : 13, // The number of lines to draw
            length : 7, // The length of each line
            width : 4, // The line thickness
            radius : 10, // The radius of the inner circle
            corners : 1, // Corner roundness (0..1)
            rotate : 0, // The rotation offset
            color : '#000', // #rgb or #rrggbb
            speed : 1, // Rounds per second
            trail : 60, // Afterglow percentage
            shadow : false, // Whether to render a shadow
            hwaccel : false, // Whether to use hardware acceleration
            className : 'spinner', // The CSS class to assign to the spinner
            zIndex : 2e9, // The z-index (defaults to 2000000000)
            top : $(window).height()/2.5, // Manual positioning in viewport
            left : "auto"
        };
        var target = $("body")[0];
        return new Spinner(opts).spin(target);
     },
     "stop" : function(spinner){
        spinner.stop();
     }
};

When the DOM is loaded, I start spinning:

$(document).ready(function(){
        // Once the DOM is loaded, start spinning
        spinner = Rats.UI.LoadAnimation.start();

        pageUI();

});

When the entire page is loaded, I stop spinning:

$(window).load(function(){
        // Once the page is fully loaded, stop spinning
        Rats.UI.LoadAnimation.stop(spinner);
});

What's the difference between window.onload vs $(document).ready()

See the full code on my github repo:

• https://github.com/seahrh/sgratrace/blob/master/war/js/rats.js
• https://github.com/seahrh/sgratrace/blob/master/war/index.html