custom-mosaico-toolbar-button.js

plugins.push(function(viewModel) {
    var addMyButton = function() {
        var $toobarRightButtons = $('#toolbar .rightButtons');
        if (!$toobarRightButtons.length) {
            setTimeout(addMyButton, 50);
            return;
        }
        $('<a title="Hello" class="ui-button ui-corner-all ui-widget" role="button">\
            <span class="ui-button-icon ui-icon fa fa-fw fa-times-circle"></span>\
            <span class="ui-button-icon-space"></span>Hello\
          </a>')
        .appendTo($toobarRightButtons)
        .css('color', 'white', '!important')
        .on('click', function() {
            alert('Yay!');
        });
    };
    addMyButton();
});

Thanks, this was a lifesaver.

How can i use this code? I put it in mosaico.min.js and also create a new js file and embed it with mosaico. In both way this did'not work for me. Can you please help me out this?

If anyone is new to mosaico and node, like me, and is reading this wondering where to add this code, I've just added it to line 27 of /html/editor.html underneath plugins = [function(vm) {window.viewModel = vm;}]; (uncomment this line), and it works just fine :)