How to vertically and horizontally align any block element on the screen with Javascript

main.js

// vertically and horizontally center a block on the browser screen
function centerBlock ($block){
    var top = Math.floor(($(window).height() - $block.height())/2);
    var left = Math.floor(($(window).width() - $block.width())/2);
    $block.css('margin', top+'px '+left+'px');
}

// use it
centerBlock($('.myblock'));
$(window).resize(function(){
    centerBlock($('.myblock'));
});