chrome-page-eval
v1.3.2
Published
Evaluate a script function on a page with Chrome
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chrome-page-eval
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]*/ })puppeteer[required] - the exported module from puppeteer that your app is going to use- properties with any of the launch options supported by puppeteer
Evaluate options
const puppeteer = require('puppeteer')
const chromePageEval = require('chrome-page-eval')
const chromeEval = chromePageEval({ puppeteer })
(async () => {
const result = await chromeEval({ /*[evaluate options here]*/ })
})()htmlstring [required] - the path to the html file to load in a Chrome pagescriptFnstring [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}'viewportobject - object with any of the viewport options supported by puppeteerargsarray - a list of custom arguments to pass to thescriptFnfunction. ex:args: [1, 2]and withscriptFn: function (a, b) { return a + b}'will produce3as resultstylesarray - array of css strings to insert at the beginning of page's head element. ex:styles: ['* { font-family: 'Calibri'; font-size: 16px; }']waitForJSboolean - whentruethescriptFnwon't be executed until the variable specified inwaitForJSVarNameoption is set to true in page's javscript. defaults tofalsewaitForJSVarNamestring - name of the variable that will be used as trigger ofscriptFn. defaults to"CHROME_PAGE_EVAL_READY"waitUntilstring - a value that specifies when a page is considered to be loaded, for the list of all possible values and its meanings seewaitUntiloption in puppeteer docs. defaults to the the default value of puppeteertimeoutnumber - time in ms to wait for the script evaluation to complete, when the timeout is reached the evaluation is cancelled. defaults to30000
Requirements
- Install puppeteer >= 1.0.0 with
npm install puppeteer --savein your project and pass it tochrome-page-evalconstructor function.
Caveats
- What you return in your script function (
scriptFnoption) must be a serializable value in order to receive it properly, if a non serializable value is returned you will getundefinedas 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 useset 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_DEBUGGINGenv var:CHROME_PAGE_EVAL_DEBUGGING=true node [your-entry-file-here].js(on Windows useset CHROME_PAGE_EVAL_DEBUGGING=true && node [your-entry-file-here].js).
License
See license