// Modify global object at the page initialization. // In this example, effectively Math.random() always returns 0.42. "use strict"; var page = require('webpage').create(); page.onInitialized = function () { page.evaluate(function () { Math.random = function() { return 42 / 100; }; }); }; page.open('http://ariya.github.com/js/random/', function (status) { var result; if (status !== 'success') { console.log('Network error.'); } else { console.log(page.evaluate(function () { return document.getElementById('numbers').textContent; })); } phantom.exit(); });