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chrome-page-eval

1.3.0 • Public • Published

chrome-page-eval

NPM Version License Build Status

Evaluate a script function on a page with Chrome

This module let you evaluate a script function on a page using Chrome (controlled with puppeteer) 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 puppeteer = require('puppeteer')
const chromePageEval = require('chrome-page-eval')
const chromeEval = chromePageEval({ puppeteer })
 
(async () => {
  try {
    const result = await chromeEval({
      html: '/path/to/sample.html',
      scriptFn: `
        function () {
          let title = document.title
 
          let content = Array.from(document.querySelectorAll('.content'), (node) => {
            return node.textContent
          })
 
          return {
            title,
            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 chromePageEval = require('chrome-page-eval')
const chromeEval = chromePageEval({ /*[constructor options here]*/ })

Evaluate options

const puppeteer = require('puppeteer')
const chromePageEval = require('chrome-page-eval')
const chromeEval = chromePageEval({ puppeteer })
 
(async () => {
  const result = await chromeEval({ /*[evaluate options here]*/ })
})()
  • html string [required] - the path to the html file to load in a Chrome page
  • scriptFn string [required] - the script to evaluate in the Chrome page. the script must be a function that returns a value. ex: scriptFn: 'function () { return 1 + 2}'
  • viewport object - object with any of the viewport options supported by puppeteer
  • 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
  • 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 "CHROME_PAGE_EVAL_READY"
  • waitUntil string - a value that specifies when a page is considered to be loaded, for the list of all possible values and its meanings see waitUntil option in puppeteer docs. defaults to the the default value of puppeteer
  • 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

  • Install puppeteer >= 1.0.0 with npm install puppeteer --save in your project and pass it to chrome-page-eval constructor function.

Caveats

  • What you return in your script function (scriptFn option) must be a serializable value in order to receive it properly, 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=chrome-page-eval* node [your-entry-file-here].js (on Windows use set DEBUG=chrome-page-eval* && node [your-entry-file-here].js). This will print out to the console some additional information about what's going on.

  • To see the Chrome instance created (the visible chrome window) run your app with the CHROME_PAGE_EVAL_DEBUGGING env var: CHROME_PAGE_EVAL_DEBUGGING=true node [your-entry-file-here].js (on Windows use set CHROME_PAGE_EVAL_DEBUGGING=true && node [your-entry-file-here].js).

License

See license

Install

npm i chrome-page-eval

DownloadsWeekly Downloads

1,071

Version

1.3.0

License

MIT

Unpacked Size

23.5 kB

Total Files

13

Last publish

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