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<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Diggernaut: Documentation for Meta-Language | Basic Settings | Turning On Selenium</title>
<meta name="description" content="How to use the headless browser with Selenium to fetch pages before scraping.">
<meta name="keywords" content="Diggernaut, scraping, web scraping, scraper, web scraper, meta-language, make scraper, scraper for websites, learning to scrape, data acquisition, create scraper, online scraper, content scraper, scraper for shop, scraper for classifieds, coding scraper, selenium">
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<div class="container">
<h1>Basic Settings</h1>
<div>
<h2>Turning On Selenium</h2>
<p class="flow-text">
Most of the tasks you meet can be solved without using the <a href="https://en.wikipedia.org/wiki/Headless_browser" target="_blank">headless blowser</a>.
Generally using standard mechanics for fetching pages is always better: its faster, consume less resources, give you more control over the process of fetching etc.
But there are cases when using real browser with JS support is your only solution.
</p>
<p class="flow-text">
For such cases, you can use Selenium with Chrome Web Driver, but please note that when you request a single page, Selenium also fetches many other
supplementary files and data, like JavaScripts or AJAX requests. You will be charged 1 page request for every successfull (when server returns response code 200)
document type HTTP request and any other type of request that returns content with mime-types: text/html, text/plain or application/json.
Therefore, downloading one page with Selenium can cost you dozens of page requests. To enable Selenium use the <span class = "hlt2">js_enabled</span> option:
</p>
<div class="row">
<div class="col s12">
<pre class="language-yaml">
<code class="language-yaml"># TURNING ON SELENIUM
- config:
js_enabled: "yes"
</code></pre>
</div>
</div>
<span class="spacer"></span>
<p class="flow-text">
You can use the <span class = "hlt2">Walk</span> command to navigate pages. However, it must be remembered that when using this command,
only GET requests are supported in Selenium (including iteration through the link pool).
</p>
<blockquote class="warning darken-1">
<p class="flow-text">
<strong>Please note:</strong><br/>
Working with a DOM structure in Selenium is different from working with the basic mechanics of Diggernaut. You can use the <span class = "hlt2">Find</span>
command to navigate the DOM. However, in some cases, when you are iterating over a pool of found elements, they may be invalidated if the browser
re-renders the DOM.
</p>
</blockquote>
<p class="flow-text">
When entering a block, you can use all the commands of the block context. As well as some additional commands that work only in Selenium:
</p>
<table class="responsive-table highlight">
<thead>
<tr>
<th data-field="parameter">Command</th>
<th data-field="description">Description</th>
</tr>
</thead>
<tbody>
<tr>
<td>type</td>
<td>Simulates text input to the current element (block). Mainly used to fill out form fields.</td>
</tr>
<tr>
<td>submit</td>
<td>Simulates sending a form on the selected item. Mostly used to send the completed form.</td>
</tr>
<tr>
<td>click</td>
<td>Simulates a mouse click on the current element. It is used to follow links, click on buttons, set focus (cursor) on text fields of a form to fill them with text. Attention: when following a link, this command does not generate a new page context, but replaces the current one.</td>
</tr>
<tr>
<td>scrollto</td>
<td>Scrolls to the currently selected element. Can be used when you need to click on some element, but it's out of the browser window visibility frame.</td>
</tr>
<tr>
<td>execute</td>
<td>Executes JavaScript snippet passed with js argument. It can be used to manipulate page elements, eg to hide or show something.</td>
</tr>
<tr>
<td>fetch_content</td>
<td>Fetches HTML content of the selected frame.</td>
</tr>
<tr>
<td>screenshot</td>
<td>Makes a screenshot of the browser screen and puts the base64-encoded image into a register.</td>
</tr>
</tbody>
</table>
<div class="row">
<div class="col s12">
<pre class="language-yaml">
<code class="language-yaml">#FETCH IFRAME CONTENT AND SAVE TO VARIABLE
- find:
path: 'div[id*="google_ads_iframe"] > iframe, .onf-ad iframe,[id*=moneytag] iframe, [id*=scr_] iframe, #grumi-container iframe'
do:
- fetchcontent
- variable_set: ad
#HIDE STICKY HEADER
- execute:
js: "document.querySelector('[data-widget=\"webStickyProducts\"] > div').hidden = true;"
# FIND A TEXT FIELD
- find:
path: input[name="username"]
do:
# SCROLLING TO THE FIELD
- scrollto
# SET THE FOCUS TO THE FIELD
- click
# TYPE IN THE TEXT
- type: iamyouruser
# SUBMIT THE FORM
- submit
</code></pre>
</div>
</div>
<p class="flow-text">
If you have enabled the Selenium support option, you can also work using the standard page collection mechanics. To do this, switch the currently
used engine. And when Selenium is needed, switch back to Selenium. This will allow you to build applications for working with different sources
and APIs within the same digger. To switch the engine, use the command <span class="hlt2">set_engine</span>.
</p>
<div class="row">
<div class="col s12">
<pre class="language-yaml">
<code class="language-yaml"># SWITCH TO THE STANDARD ENGINE
- set_engine: surf
# SWITCH TO THE SELENIUM ENGINE
- set_engine: selenium
</code></pre>
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