Documentation

Infinite scrolling: detect the end of a feed (PHP)

Collect products from a feed that loads content as the page scrolls. Track the visible card count and check the completeness of the final list.

Choose PHP, paste the complete source from this article and set the run parameters below. The source for this collection is ScrapingCourse. This walkthrough applies to the specified demonstration page.

Example settings

{
  "path": "/infinite-scrolling",
  "mode": "scroll",
  "expected": 147
}

path selects the page, mode selects an algorithm branch, and expected sets the control count for this example. It is not a plan limit. When the source dataset changes, check the expected count against it.

How the algorithm works

Open /infinite-scrolling in a browser and wait for the first nonempty product name.
Call scroll(3, 400) inside the loop: three scroll steps with a 400-millisecond pause between steps. The second argument is not a pixel distance.
Read the current HTML and collect products after scrolling. seen retains every unique product encountered during this run.
Compare the current DOM card count with the previous value. Increment stable only when the count is unchanged; reset it when the count changes.
Finish after three consecutive unchanged observations. A separate limit allows at most 40 loop iterations.
Read the final page again, compare the result with expected and close the browser regardless of the outcome.

Products are processed by courseCollect($ctx, $html, $seen). Read the name first, skip empty names, and use the card link as the key, falling back to the name when necessary. seen prevents the same key being emitted twice. This matters when a later HTML read includes products already collected.

Details that matter

The page card count and the number of newly emitted rows are different. stable tracks cards, while expected is checked against unique keys in seen.

PHP details

PHP calls network and browser methods sequentially with ->. courseCollect receives $seen and returns its updated array, so assign each result back. Close the page in finally; $ctx->fail() stops the run with a readable message.

Expected output

The configured demonstration dataset expects 147 unique records. The final check compares the actual unique key count with expected.

Field	Contents
`name`	Product name with leading and trailing whitespace removed.
`price`	Price converted from text to a number.
`image`	Image URL read from the card src attribute.

Complete scenario source

The source is shared by this collection. This example runs its scroll branch using the parameters above. Copy the complete block into the PHP editor; no fixed sign-in credentials or service keys need to be added.

<?php

function run(\Sdk\Context $ctx): void
{
    $origin = 'https://www.scrapingcourse.com';
    $path = (string) $ctx->param('path', '/pagination');
    $mode = (string) $ctx->param('mode', 'http');
    $auto = $ctx->param('auto_captcha', true) !== false;
    $seen = [];
    if ($mode === 'http') {
        $url = $origin.$path;
        $visited = [];
        while ($url !== null && count($visited) < 50) {
            if (isset($visited[$url])) {
                $ctx->fail('Pagination returned an already processed page');
            }
            $visited[$url] = true;
            $response = $ctx->http()->withoutCache()->get($url, $auto);
            if (! $response->ok()) {
                $ctx->fail('The source could not be opened: '.$response->status);
            }
            $html = $response->body;
            $seen = courseCollect($ctx, $html, $seen);
            $next = $ctx->dom($html)->attr('a[rel="next"], a.next.page-numbers', 'href');
            $url = $next ? $ctx->url()->absolutize($url, $next) : null;
        }
        if ($url !== null) {
            $ctx->fail('The pagination safety limit was reached');
        }
    } else {
        $page = $ctx->browser()->open($origin.$path, ['*/ajax/products*'], [], $auto);
        try {
            if ($mode === 'login') {
                $dom = $ctx->dom($page->content());
                $hint = '';
                foreach ($dom->qa('p') as $p) {
                    if (str_contains($p->text(), 'Demo Credentials:')) {
                        $hint = $p->text();
                    }
                }
                preg_match('/Password:\s*([^\s|]+)/i', $hint, $password);
                preg_match('/Email:\s*([^\s|]+@[^\s|]+)/i', $hint, $emailMatch);
                $email = $emailMatch[1] ?? '';
                if ($email === '' || ! isset($password[1])) {
                    $ctx->fail('The page does not contain demo credentials');
                }
                $page->type('#email', $email)->type('#password', $password[1])->click('button[type="submit"]');
            }
            if ($mode === 'challenge') {
                $text = preg_replace('/\s+/', ' ', $ctx->dom($page->content())->text('body') ?? '');
                if (! preg_match('/You (?:successfully )?bypassed|successfully bypassed|Congratulations/i', $text)) {
                    $ctx->fail('The expected page content was not received');
                }
                $ctx->emit(['name' => $path, 'passed' => true], $path);
            } else {
                $page->waitFor('.product-name:not(:empty)', 15000);
                if ($mode === 'button') {
                    $complete = false;
                    for ($i = 0; $i < 30; $i++) {
                        $html = $page->content();
                        $before = $ctx->dom($html);
                        $seen = courseCollect($ctx, $html, $seen);
                        $button = $before->q('#load-more-btn');
                        if ($button === null || preg_match('/display:\s*none/', $button->attr('style') ?? '')) {
                            $complete = true;
                            break;
                        }
                        $offset = $button->attr('data-offset');
                        $count = count($before->qa('.product-item'));
                        $page->click('#load-more-btn');
                        $response = $page->waitForResponse('*offset='.$offset, 15000);
                        if ($response === null || ($response['status'] < 200 || $response['status'] >= 300) || $response['truncated'] || $response['error']) {
                            $ctx->fail('The next batch could not be loaded');
                        }
                        if (trim($response['body'] ?? '') === '') {
                            $complete = true;
                            break;
                        }
                        $page->waitFor('.product-item:nth-child('.($count + 1).')');
                    }
                    if (! $complete) {
                        $ctx->fail('The batch loading safety limit was reached');
                    }
                }
                if ($mode === 'scroll') {
                    $stable = 0;
                    $previous = 0;
                    for ($i = 0; $i < 40 && $stable < 3; $i++) {
                        $page->scroll(3, 400);
                        $html = $page->content();
                        $seen = courseCollect($ctx, $html, $seen);
                        $count = count($ctx->dom($html)->qa('.product-item'));
                        $stable = $count === $previous ? $stable + 1 : 0;
                        $previous = $count;
                    }
                    if ($stable < 3) {
                        $ctx->fail('The feed is still loading: increase the scroll limit');
                    }
                }
                $seen = courseCollect($ctx, $page->content(), $seen);
            }
        } finally {
            $page->close();
        }
    }
    $expected = (int) $ctx->param('expected', 1);
    if ($mode !== 'challenge' && count($seen) !== $expected) {
        $ctx->fail('Incomplete result: '.count($seen).' instead of '.$expected);
    }
}

function courseCollect(\Sdk\Context $ctx, string $html, array $seen): array
{
    $dom = $ctx->dom($html);
    foreach ($dom->qa('.product-item, li.product') as $card) {
        $name = trim($card->q('.product-name, .woocommerce-loop-product__title')?->text() ?? '');
        $key = $card->q('a')?->attr('href') ?? $name;
        if ($name === '' || isset($seen[$key])) {
            continue;
        }
        $seen[$key] = true;
        $ctx->emit(['name' => $name, 'price' => $ctx->text()->money($card->q('.product-price, .price')?->text() ?? ''),
            'image' => $card->q('img')?->attr('src') ?? ''], $key);
    }

    return $seen;
}