mixpanel = require('mixpanel')

var api_key = 'YOUR API KEY',
    api_secret = 'YOUR API SECRET';

var mx = new mixpanel({
    api_key: api_key,
    api_secret: api_secret
});

mx.request(
    'button click',
    {
        type: 'unique',
        interval: 7,
        unit: 'day'
    },
    function(error, data) {
        console.dir(data);
    }
        
)