Is there a way to add script to add new functions in evaluate() context of chrome+puppeeter?

Question

Based on this response, is there a way (like with casperjs/phantomjs) to add our custom functions in page.evaluate() context ?

By example, include a file with a help

Answer 1

Another solution based on casperjs getElementByXPath() and getElementsByXPath(). The advantage is that we can use an xpath expression against a particular node (second argument).

window.$x = xPath => document
    .evaluate(
        xPath,
        document,
        null,
        XPathResult.FIRST_ORDERED_NODE_TYPE,
        null
    )
    .singleNodeValue;

window.getElementByXPath = function getElementByXPath(expression, scope) {
    scope = scope || document;
    var a = document.evaluate(expression, scope, null, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
    if (a.snapshotLength > 0) {
        return a.snapshotItem(0);
    }
};

window.getElementsByXPath = function getElementsByXPath(expression, scope) {
    scope = scope || document;
    var nodes = [];
    var a = document.evaluate(expression, scope, null, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
    for (var i = 0; i < a.snapshotLength; i++) {
        nodes.push(a.snapshotItem(i));
    }
    return nodes;
};

Real life code sample :

const puppeteer = require('puppeteer');

(async () => {

    const browser = await puppeteer.launch();
    const page = await browser.newPage();

    await page.goto('https://99bitcoins.com/bitcoin-rich-list-top100/#addresses', { waitUntil: 'networkidle2' });
    await page.addScriptTag({ path: './helperFunctions.js' });

    const result = await page.evaluate(() => {
        var obj = {};
        var data = getElementsByXPath('//table[@class="t99btc-rich-list"]//tr');
        for (var i = 1; i<=100; i++) {
           obj[i] = {
               "hash": getElementByXPath('./td/a', data[i]).innerText,
               "balance": getElementByXPath('./td[3]', data[i]).innerText
           }
        }

        return obj;

    });
    console.log(JSON.stringify(result, null, 4));
    await browser.close();

})();