Disable Space Key

How to block the space key from going down the page when pressed ?

$(document).keydown(function(e) {
    if (e.keyCode == 32) { 
        return false;
    }
});

This code keeps dropping the bar when you press Space

I have this script Q makes it stop, but I didn't understand the difference of the Code:

/**
 * $.disablescroll
 * Author: Josh Harrison - aloofdesign.com
 *
 * Disables scroll events from mousewheels, touchmoves and keypresses.
 * Use while jQuery is animating the scroll position for a guaranteed super-smooth ride!
 */
;(function($) {
    "use strict";

    // Privates
    var instance;
    var _handleKeydown = function(event) {
        for (var i = 0; i < this.opts.scrollEventKeys.length; i++) {
            if (event.keyCode === this.opts.scrollEventKeys[i]) {
                event.preventDefault();
                return;
            }
        }
    };    

    var _handleWheel = function(event) {
        event.preventDefault();
    };

    // The object      
    function UserScrollDisabler($container, options) {    

        // spacebar: 32, pageup: 33, pagedown: 34, end: 35, home: 36
        // left: 37, up: 38, right: 39, down: 40
        this.opts = $.extend({
            handleKeys : true,
            scrollEventKeys : [32, 33, 34, 35, 36, 37, 38, 39, 40]
        }, options);      
        this.$container = $container;
        this.$document = $(document);
        this.disable();
    }
    UserScrollDisabler.prototype = {
        disable : function() {
            var t = this;
            if(t.opts.handleKeys) {
                t.$document.on("keydown.UserScrollDisabler", function(event) {
                    _handleKeydown.call(t, event);
                });
            }
        },
        undo : function() {
            var t = this;
            t.$container.off(".UserScrollDisabler");
            if(t.opts.handleKeys) {
                t.$document.off(".UserScrollDisabler");
            }
        }
    };    
    // Plugin wrapper for object   

    $.fn.disablescroll = function(method) {  
        // If calling for the first time, instantiate the object and cache in this closure.
        // Plugin can therefore only be instantiated once per page.
        // Can pass options object in through the method parameter.
        if( ! instance && (typeof method === "object" || ! method)) {
            instance = new UserScrollDisabler(this, method); // this = jquery collection to act on = $(window), hopefully!
        }
        // Instance already created, and a method is being explicitly called, e.g. .disablescroll('undo');
        else if(instance && instance[method]) {
            instance[method].call(instance);
        }    
        // No method called explicitly, so assume 'disable' is intended.
        // E.g. calling .disablescroll(); again after a prior instantiation and undo.
        else if(instance) {
            instance.disable.call(instance);
        }   
    };
})(jQuery);