带有节点的Phantomjs给出“未决承诺”

Question

When I run the script below from the command line node script.js , the result is:

success
Promise { <pending> }

The page never gets opened in console.log , can anyone explain why?

var phantom = require('phantom');

phantom.create().then(function (ph) {
  ph.createPage().then(function (page) {
    page.open('https://stackoverflow.com/').then(function (status) {
      console.log(status);
      var p = page.evaluate(function () {
        return document.getElementsByTagName('html')[0].innerHTML
      });
      console.log(p);
    });
  });
});

Answer 1

That's because you're assigning Promise to a variable, and it's result is not returned immediately. You should rather:

page.evaluate(function () {
  return document.getElementsByTagName('html')[0].innerHTML;
}).then(function (html) {
  console.log(html);
});

Also, to not get lost in callback hell you might try to use async/await approach:

(async () => {
  const instance = await phantom.create();

  const page = await instance.createPage();

  const status = await page.open('https://stackoverflow.com/');

  const html = await page.evaluate(function () {
    return document.getElementsByTagName('html')[0].innerHTML;
  });

  console.log(html);
})();

Which is kind of preferred way according to phantom maintainers guide.

Answer 2

as displayed, page.evaluate returns a promise.

try the folowing code :

var phantom = require('phantom');
phantom.create().then(function(ph) {
  ph.createPage().then(function(page) {
    page.open('https://stackoverflow.com/').then(function(status) {
      console.log('test'+status);
      var p = page.evaluate(function () {
                 return document.getElementsByTagName('html')[0].innerHTML
             });
      p.then(function(pagecontent) {
        console.log(pagecontent);
        process.exit()
      });
    });
  });
});