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@rosshinkley @GautierT
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Using Promises

Native promises are the preferred method for using Nightmare. The following example searches for github nightmare at Yahoo and returns the first HREF in the search results:

var Nightmare = require('nightmare'),
  nightmare = Nightmare({
    show: true
  });

nightmare
  //load a url
  .goto('http://yahoo.com')
  //simulate typing into an element identified by a CSS selector
  //here, Nightmare is typing into the search bar
  .type('input[title="Search"]', 'github nightmare')
  //click an element identified by a CSS selector
  //in this case, click the search button
  .click('#uh-search-button')
  //wait for an element identified by a CSS selector
  //in this case, the body of the results
  .wait('#main')
  //execute javascript on the page
  //here, the function is getting the HREF of the first search result
  .evaluate(function() {
    return document.querySelector('#main .searchCenterMiddle li a')
      .href;
  })
  //end the Nightmare instance along with the Electron instance it wraps
  .end()
  //run the queue of commands specified, followed by logging the HREF
  .then(function(result) {
    console.log(result);
  })
  //catch errors if they happen
  .catch(function(error){
    console.error('an error has occurred: ' + error);
  });

Running multiple steps

Promises are useful for chaining multiple steps together using .then(). Say we wanted to change the Yahoo example to get the first link from the first and second result page:

var Nightmare = require('nightmare'),
  nightmare = Nightmare({
    show: true
  });

nightmare
  //load a url
  .goto('http://yahoo.com')
  //simulate typing into an element identified by a CSS selector
  //here, Nightmare is typing into the search bar
  .type('input[title="Search"]', 'github nightmare')
  //click an element identified by a CSS selector
  //in this case, click the search button
  .click('#uh-search-button')
  //wait for an element identified by a CSS selector
  //in this case, the body of the results
  .wait('#main')
  //execute javascript on the page
  //here, the function is getting the HREF of the first search result
  .evaluate(function() {
    return document.querySelector('#main .searchCenterMiddle li a')
      .href;
  })
  //run the queue of commands specified, followed by logging the HREF
  .then(function(result) {
    console.log(result);
  })
  .then(function() {
    //since Nightmare has an internal `.then()`, return the instance returned by the final call in the chain
    return nightmare
      //click the next button to get the next page of search results
      .click('.next')
      //get the first HREF from the second page of results
      .evaluate(function() {
        return document.querySelector('#main .searchCenterMiddle li a')
          .href;
      })
  })
  .then(function(result) {
    //log the second page search result's HREF
    console.log(result);
    
    //queue ending the Nightmare instance along with the Electron instance it wraps
    //again, return the instance to leverage the internal `.then()`
    return nightmare.end();
  })
  //run the queue of commands specified
  //in this case, `.end()`
  .then(function() {
    console.log('done');
  })
  //catch errors if they happen
  .catch(function(error){
    console.error('an error has occurred: ' + error);
  });

Note that the Nightmare instance is getting returned. Again, Nightmare exposes an internally defined version of .then() that can be leveraged to get the desired behavior.

References

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