phantom-page-eval

Evaluate a script function on a page with PhantomJS

2.0.1
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Version published: 2 years ago

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Created: 7 years ago

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phantom-page-eval

Evaluate a script function on a page with PhantomJS

This module let you evaluate a script function on a page using PhantomJS and get the return value of the evaluation in node.

Usage

<!-- sample.html -->
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Test page</title>
</head>
<body>
  <div class="content">1</div>
  <div class="content">2</div>
  <div class="content">3</div>
  <div class="content">4</div>
</body>
</html>

const phantomPath = require('phantomjs').path
const phantomPageEval = require('phantom-page-eval')
const phantomEval = phantomPageEval({ phantomPath })

(async () => {
  try {
    const result = await phantomEval({
      html: '/path/to/sample.html',
      scriptFn: `
        function () {
          var title = document.title
          var content = Array.prototype.slice.call(document.getElementsByClassName('content'))

          content = content.map(function (node) {
            return node.textContent
          })

          return {
            title: title,
            content: content
          }
        }
      `
    })

    console.log(result.title) // -> Test page
    console.log(result.content) // -> [1, 2, 3, 4]
  } catch (e) {
    console.error('Error while trying to evaluate script:', e)
  }
})()

Constructor options

const phantomPageEval = require('phantom-page-eval')
const phantomEval = phantomPageEval({ /*[constructor options here]*/ })

phantomPath string [required] - the path to the phantomjs executable that your app is going to use
tmpDir string - the directory path that the module is going to use to save temporary files needed during the evaluation. defaults to require('os').tmpdir()
clean boolean - specifies if the module should delete any temp file automatically after an evaluation, if false temp files will not be cleaned by the module and app developer will be responsible to clean them. defaults to true
launchArgs array - array with any of the command line options supported by phantomjs. defaults to ['--ignore-ssl-errors=yes', '--web-security=false', '--ssl-protocol=any']

Evaluate options

const phantomPath = require('phantomjs').path
const phantomPageEval = require('phantom-page-eval')
const phantomEval = phantomPageEval({ phantomPath })

(async () => {
  const result = await phantomEval({ /*[evaluate options here]*/ })
})()

html string [required] - the path to the html file to load in a phantom page
scriptFn string [required] - the script to evaluate in the phantom page. the script must be a function that returns a value. ex: scriptFn: 'function () { return 1 + 2}'
styles array - array of css strings to insert at the beginning of page's head element. ex: styles: ['* { font-family: 'Calibri'; font-size: 16px; }']
waitForJS boolean - when true the scriptFn won't be executed until the variable specified in waitForJSVarName option is set to true in page's javscript. defaults to false
waitForJSVarName string - name of the variable that will be used as trigger of scriptFn. defaults to "PHANTOM_PAGE_EVAL_READY"
viewport object - object with any of the viewportSize options supported by phantomjs
args array - a list of custom arguments to pass to the scriptFn function. ex: args: [1, 2] and with scriptFn: function (a, b) { return a + b}' will produce 3 as result
timeout number - time in ms to wait for the script evaluation to complete, when the timeout is reached the evaluation is cancelled. defaults to 30000

Requirements

Have available a phantomjs executable. you can download phantomjs and get access to the path to the executable by doing: npm install phantomjs --save or npm install phantomjs-prebuilt --save and then in your project call require('phantomjs').path and pass it to phantom-page-eval constructor function.

Caveats

What you return in your script function (scriptFn option) must be a serializable value recognized by phantomjs in order to receive it properly (normal javascript primitives like object, arrays, string, booleans, etc are good), if a non serializable value is returned you will get undefined as the result.

Debugging

To get more information (internal debugging logs of the module) about what's happening during the evaluation on the page start your app in this way: DEBUG=phantom-page-eval* node [your-entry-file-here].js (on Windows use set DEBUG=phantom-page-eval* && node [your-entry-file-here].js). This will print out to the console some additional information about what's going on.

License

See license

Keywords

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Package last updated on 09 Jun 2022

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