// require() some stuff from npm (like you were using browserify)
// and then hit Rebuild to run it on the right
var immstruct = require('immstruct');
var structure = immstruct({foo: {bar: 'hello'}});

//update the cursor
structure.cursor('foo').update('bar', function () { return 'newbar' });

//set new key in immutable data structure
structure.cursor('foo').set('baz', 'foobaz');
alert(JSON.stringify(structure.cursor('foo').toJSON()));