Леонид Князев

$(".map-show").hover(function () {
        var map = $(this).attr("data-map");
        var map_width = $(window).width();
        var map_height = $(this).attr("data-map-height");
        $(this).css("height", map_height);
        if (map_width > window) { map_width = window; }
        $(this).html('<iframe src="' + map + '" width="' + map_width + '" height="' + map_height + '" frameborder="0" style="border:0" allowfullscreen></iframe>');

        $(this).off('mouseenter mouseleave');
});

const elems = document.querySelectorAll('[id^=elem-]');

const str = 'Hello! Wor!ld!';
document.write(str.replace(/!/g, ''));

Compiling in the browser has a fairly limited use case, so if you are working on a production site you should be precompiling your scripts server-side.