PhantomJS cannot access member 'evaluate' of deleted QObject

Question

function checkMessages(user, password, callback) {  
    var page = require('webpage').create();  
    page.open('http://mywebpage.com', function (status) {  
        if (status === 'fail') {  
            console.log(user + ': ?');  
        } else {  
            page.evaluate(function (user, password) {  
                document.querySelector('input[name=username]').value = user;  
                document.querySelector('input[name=password]').value = password;  
                document.querySelector('button[name=yt0]').click();  
            }, user, password);  
            waitFor(function() {  
                return page.evaluate(function() {  
                    var el = document.getElementById('fancybox-wrap');  
                    if (typeof(el) != 'undefined' && el != null) {  
                        return true;  
                    }  
                    return false;  
                });  
            }, function() {  
                var messageCount = page.evaluate(function() {  
                    var el = document.querySelector('span[class=unread-number]');  
                    if (typeof(el) != 'undefined' && el != null) {  
                        return el.innerText;  
                    }  
                    return 0;  
                });  
                console.log(messageCount);  
            });  
        }  
        page.close();  
        callback.apply();  
    });
}

For some reason, I just can't get this to work. PhantomJS is complaining: "Error: cannot access member 'evaluate' of deleted QObject". Is it because I am having multiple page.evaluates?

Answer 1

PhantomJS is asynchronous. In this case waitFor() is asynchronous, so you need to close the page after you've done with it. You need to move

page.close();
callback.apply();

into the last function that will be executed which is the callback of waitFor() . You might want to change waitFor a little bit, so that there is another callback when the timeout is reached which is the error branch which also requires the page closing and callback:

function waitFor(testFx, onReady, timeOutMillis) {
    var maxtimeOutMillis = timeOutMillis ? timeOutMillis : 3000,
        start = new Date().getTime(),
        condition = false,
        interval = setInterval(function() {
            if ( (new Date().getTime() - start < maxtimeOutMillis) && !condition ) {
                condition = testFx();
            } else {
                var error = null;
                if(!condition) {
                    error = "'waitFor()' timeout";
                    console.log(error);
                } else {
                    console.log("'waitFor()' finished in " + (new Date().getTime() - start) + "ms.");
                    clearInterval(interval);
                }
                onReady(error);
            }
        }, 250);
};