phantomjs history.back

back.js

var flag = false;

var page = require('webpage').create();

page.onLoadFinished = function() {
    flag = !flag;
    if (flag) {
        console.log('jump to google');
        page.evaluate(function() {
            window.location.href = 'http://www.google.com/';
        });
    } else {
        console.log('go back');
        page.evaluate(function() {
            window.history.back();
        });
    }
}

page.open('http://www.bing.com/');