Javascript Debut - From Chrome Console To A Bookmarklet

I am new to JS and am trying to write a simple bookmarklet for a website that has divs with class 'collapseable' set to display: none; I want by one click to set all elements with

Solution 1:

When I tried making a bookmarklet myself, I had the same problem. My solution was to use void (function({ /* your code */ })().

javascript:void(function(){
    var getElsByCN = document.getElementsByClassName ||
        function(classname, node)  {
            if(!node) node = document.body;
            var a = [],
                re = newRegExp('\\b' + classname + '\\b'),
                els = node.getElementsByTagName("*");
            for (var i = 0, j = els.length; i < j; i++)
                if (re.test(els[i].className))
                    a.push(els[i]);
            return a;
        };
    var elems = getElsByCN('collapseable');
    for (var i = 0; i < elems.length; i++)
       elems[i].style.display = 'block';
)();

This works because it returns an undefined value due to the use of void. When your script wrote block on the page, it was likely because that was the last value set/accessed by the funtion.