JavaScript && operator in visual editor

You should use wp_enqueue_script for your javascript files instead of adding the code directly into the post content.

ps:
You can check out the callbacks on the the_content filter, using

add_action('wp_footer',function(){
        global $wp_filter;
        printf('<pre>%s</pre>',print_r( $wp_filter['the_content'],true));
});

to display them in the footer part of your theme. Then you will see callbacks like
wpautop, wptexturize, convert_chars and convert_smilies.

I don’t recommend it, but it is possible to remove these filters to use javascript code in the post content:

add_action('init','custom_init');
function custom_init() {
    remove_filter('the_content', 'wpautop');
    remove_filter('the_content', 'wptexturize');
    remove_filter('the_content', 'convert_chars');
    remove_filter('the_content', 'convert_smilies');
}