onDOMContentLoaded.js

const PHANTOM_FUNCTION_PREFIX = '/* PHANTOM_FUNCTION */';

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

page.onConsoleMessage = function(msg) {
    if (msg.indexOf(PHANTOM_FUNCTION_PREFIX) === 0) {
        eval('(' + msg + ')()');
    } else {
        console.log(msg);
    }
};

page.onInitialized = function() {
    page.evaluate(function(domContentLoadedMsg) {
        document.addEventListener('DOMContentLoaded', function() {
            console.log(domContentLoadedMsg);
        }, false);
    }, PHANTOM_FUNCTION_PREFIX + page.onDOMContentLoaded);
};

page.onDOMContentLoaded = function() {
    // your code here
    console.log('DOMContentLoaded');
    phantom.exit();
};

page.open('http://phantomjs.org/');