How can I use nightmare to execute a script before the .end() operation?

Question

Node.js

The .then() call is only executed after .end(). There is an evaluate method borrowed from PhantomJS, which executes a script with browser variables; variables with a value can be passed there, but for some reason they are not passed with the function (undefined). Task: execute the server script, passing the value from the browser, and continue the execution in the same way.
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And in addition I offer an amusing problem.
I'm trying to log in to vk.com using nightmare, but the password field does not receive focus and does not accept key events. In the markup, you can see that keyup is installed on it. If you try to overwrite it to null, then nothing will come of it, although the function is visible in the property when debugging.
What kind of protection is this, where can you learn about the principles of its operation and how can you bypass it?

nightmare
    .goto('http://vk.com')
    .type('#quick_login', vk.login)
    .type('#quick_pass', vk.pass)
    .click('#quick_login_button')
    .wait(() => {
        return document.title.search(/Диалоги/) != -1;
    })
    .evaluate(() => {
        alert('It`s cool!!!');
    })
    .end()
    .then(()=> {
        console.log('complete!');
    });

Answer 1

direct use of nightmare is not very convenient, it is more comfortable to work with it inside the generator
in your case, there may be a problem of blocking the input field by a contact, you can try something like .wait(400).type('#quick_login',vk.login).wait( 400).type('#quick_pass', vk.pass)...
And I also see at least incorrect id input of the vk, index_email, index_pass blocks, respectively.
In general, you can have a nightmare like this:

function * run() {
  let html = yield nightmare.goto(href);
  let resultEvaluate = yield nightmare.evaluate(()=>{return document.body;});
 yield nightmare.end();

Naturally, in such an execution, everything must be wrapped in a try cartch finaly and catch all errors in this way, otherwise any overdue wait will generate an error.
And yet, alerts, confirms and prompts are disabled in the nightmare, there are separate events for their processing.
Your code can most likely work if you rewrite it something like this:

nightmare
    .goto('https://vk.com')
    .type('#index_email', vk.login)
    .type('#index_pass', vk.pass)
    .click('#index_login_button')
    .wait(() => {
        return document.title.search(/Диалоги/) != -1;
    })
    .evaluate(() => {
        return 'its cool!!!';
    })
    .end()
    .then((result)=> {
        console.log(result); // its cool!!!
    })
   .catch(console.error); // будете пренебрегать обработкой ошибок и кошмар будет именно ваш , а не сайта для парсинга....