Custom cell macros in IPython Notebook

custom.js

$([IPython.events]).on('app_initialized.NotebookApp', function(){

    // Try to read JSON file specifying cell macros
    $.getJSON("/static/custom/macros.json", function(data) {
        var pickTemplateLabel = $("<span></span>")
                                .attr("class", "navbar-text")
                                .text("Cell Macro:");

        var pickTemplate = $("<select></select>").attr("id", "pick_template");

        $.each(data['cells'], function(key, cell) { 
            var option = $("<option></option>")
                         .attr("value", cell['name'])
                         .text(cell['name'])
                         .attr("code", cell['lines'].join('\n'));
            pickTemplate.append(option); 
        });

        $("div#maintoolbar-container").append(pickTemplateLabel);
        $("div#maintoolbar-container").append(pickTemplate);

        // Add a button to the toolbar for inserting a macro cell
        IPython.toolbar.add_buttons_group([
            {
                'label'   : 'Insert cell macro.',
                'icon'    : 'icon-coffee', 
                'callback': function () {
                    var code = $("select#pick_template").find(":selected").attr("code");
                    var new_cell = IPython.notebook.insert_cell_above('code');
                    new_cell.set_text(code);
                    new_cell.focus_cell();
                }
            }
        ]);
    });
});

macros.json

{
    "cells" : [
        {
            "name" : "mpl+numpy",
            "lines" : [
                "import numpy as np",
                "import matplotlib.pyplot as plt",
                "%matplotlib inline"
            ]
        },
        {
            "name" : "mpl+numpy+units",
            "lines" : [
                "import astropy.units as u",
                "import numpy as np",
                "import matplotlib.pyplot as plt",
                "%matplotlib inline"
            ]
        },
        {
            "name" : "future",
            "lines" : [
                "from __future__ import division, print_function",
                "",
                "# Standard library",
                "import time",
                "",
                "# Third-party",
                "from astropy import log as logger",
                "import emcee",
                "import matplotlib.pyplot as plt",
                "import numpy as np",
                "%matplotlib inline"
            ]
        }
    ]
}