Example code for blocking browser refreshes when using the Ace editor. Written for a blog post at https://clsc.be/1w

bindEditor.js

var edit = ace.edit('editor'); 

edit.commands.addCommand({
    name: "blockCtrlR",
    exec: function () {
        editor.promptRefresh(false);
    },
    bindKey: {mac: "cmd-r", win: "ctrl-r"}
});
edit.commands.addCommand({
    name: 'blockRefreshF5',
    exec: function () {
        editor.promptRefresh(false);
    },
    bindKey: {mac: 'f5', win: 'f5'}
});
edit.commands.addCommand({
    name: 'blockHardRefresh',
    exec: function () {
        editor.promptRefresh(true);
    },
    bindKey: {mac: 'cmd-f5', win: 'ctrl-f5'}
});

promptRefresh.js

function promptRefresh (force_reload) {
    bootbox.confirm({
        title: "Refresh Page?",
        message: "Are you sure you want to refresh this page? You may lose any work since the last time you tested your code.",
        callback: function (result) {
            if (result) {
                window.location.reload(force_reload);
            } else {
                /* Set focus back to the editor */
                ace.edit('editor').focus();
            }
        }
    });
}