Javascript Manual Pdf

[Denisha Padley]

Iam aware that JavaScript is a garbage collected language but I don't really mind freeing memory ahead of GC sweeps if it means less pressure on the GC and my application can run a little smoother/more consistently (particularly on low end devices).

No, there is no manual memory management in JavaScript, just automatic garbage collection. JavaScript was originally designed for use in browsers; if a random webpage could choose to allocate memory in such a way that the garbage collector would never reclaim it without manual intervention, that's basically asking for memory leaks (unintentional or malicious denial of service by the web page).

This isn't a reference counted language (not on any modern JS implementation), and the object tree is one way; a and b know about the object they share, but the object has no idea that it's aliased to two names. So when you forcibly free it through one alias, there's no way for the other alias to know it's now a dangling reference. Giving this sort of power to a random webpage is even worse than allowing manual allocation without GC tracking (which is basically just denial of service), because this is the sort of bug that can allow arbitrary reads and writes into process memory (once you've freed it, other stuff can get allocated there, and that dangling reference is the hacker's "in" to start taking over), eventually leading to breaking the browser sandbox and attacking the local OS.

In short: No, you can't do manual memory management, for very good reasons (yes, technically node.js could provide add-ons to JS to allow it since it's not subject to the same risks as web browsers; it does not, because the benefits aren't worth the cost of building and maintaining such a capability for only the most niche of use cases).

I need to "press" this button using JavaScript. It is no problem to get a handle to the correct button and JavaScript provides two methods focus() and click() to call both JavaScript functions that are triggered when the button is pressed manually.

if I remember correctly, it is almost 2 years by now, for me the problem was that I tried to trigger the server roundtrip in a handler method automatically called by the THTMLB Ajax library. This does not work. Do not know why exacatly, it just doesn't.

For me infact the javascript button.click() triggers the javascript function that the framework has rendered into the HTML result that is send to the browser. On this level there is no such thing as onClientClick. The onClientClick is solely on HTMLB level, but not in the HTML send to the browser.

This code might look a bit strange to those of you familiar with JavaScript, but that is because it is made to run asynchronously. In other words, browsers will not wait for the matomo.js file to be downloaded in order to show your page.

If your Matomo tracking code doesn't look like this one, you may be using the deprecated version.Older versions still work as expected and will track your visitors, but we highly recommend that you update your pages to use the most recent tracking code.

The JavaScript tracker runs on all browsers that support the JSON API. This includes IE8 and higher. Click here to see a full list of supported browsers.. If you need to support IE7 and older then you could load a polyfill that makes window.JSON available such as JSON3. This polyfill would need to be loaded before the Matomo JS tracker is loaded.

If you track multiple sub-domains in the same website, you may want your page titles to be prefixed by the sub-domain make it easy for you to see the traffic and data for each sub-domain. You can do so simply:

By default, Matomo uses the URL of the current page as the Page URL in reports. You can customise the page URL to track by using the function setCustomUrl, learn more in the FAQ How do I set a custom URL using the Matomo Javascript tracker?

However, on modern web applications, user interactions do not necessarily involve loading a new page. For example, when users click on a JavaScript link, or when they click on a tab (which triggers a JS event), or when they interact with elements of the user interface, you can still track these interactions with Matomo.

By default, Goals in Matomo are defined as "matching" parts of the URL (starts with, contains, or regular expression matching). You can also track goals for given page views, downloads, or outlink clicks.

Matomo will then send requests to count the actual time spent in the visit, as long as the user is actively viewing the page (i.e. when the tab is active and in focus). The heart beat request is executed when:

Matomo offers advanced Site Search Analytics feature, letting you track how your visitors use your internal website search engine. By default, Matomo can read URL parameters that will contain the search keyword. However, you can also record the site search keyword manually using the JavaScript function trackSiteSearch(...)

In your website, in standard pages, you would typically have a call to record Page views via matomoTracker.trackPageView(). On your search result page, you would call instead piwikTracker.trackSiteSearch(keyword, category, searchCount) function to record the internal search request. Note: the 'keyword' parameter is required, but category and searchCount are optional.

We also highly recommend setting the searchCount parameter, as Matomo will specifically report "No Result Keywords", ie. Keywords that were searched, but did not return any result. It is usually very interesting to know what users search for but can't find (yet?) on your website. Learn more about Site Search Analytics in the User Doc.

Custom variables are a powerful feature that enable you to track custom values for each visit, and/or each page view. Please see the Tracking custom variables documentation page for general information.

You can set up up to 5 custom variables (name and value) for each visit to your website, and/or up to 5 custom variables for each page view. If you set a custom variable to a visitor, when they come back one hour or two days later, it will be a new visit and their custom variables will be empty.

This function is used to create, or update a custom variable name and value. For example, imagine you want to store in each visit the gender of the user. You would store the custom variable with a name = "gender", value = "male" or "female".

Important: a given custom variable name must always be stored in the same "index". For example, if you choose to store the variable name = "Gender" in index = 1 and you record another custom variable in index = 1, then the "Gender" variable will be deleted and replaced with the new custom variable stored in index 1.

As well as tracking custom variables for "visits", it is sometimes useful to track custom variables for each page view separately. For example, for a "News" website or blog, a given article may be categorized into one or several categories. In this case, you could set one or several custom variables with name="category", one with value="Sports" and another with value="Europe" if the article is classified in Sports and Europe Categories. The custom variables report will then report on how many visits and page views were in each of your website's categories. This information can be difficult to obtain with standard Matomo reports because they report on "Best Page URLs" and "Best Page Titles" which might not contain the "category" information.

Important: It is possible to store a custom variables of scope "visit" in "index" 1, and store a different custom variable of scope "page" in the same "index" 1. Therefore, you can technically track up to 10 custom variables names and values on every page of your website (5 with a "page" scope stored in the actual page view, 5 with a "visit" scope stored in the visit).

Note: it is possible to configure Matomo so that getCustomVariable will also return the name and value of a custom variable of scope "visit", even when it was set in a previous pageview in the same visit. To enable this behavior, call the JavaScript function storeCustomVariablesInCookie before the call to trackPageView. This will enable the storage of Custom Variables of scope "visit" in a first party cookie. The custom variables cookie will be valid for the duration of the visit (30 minutes after the last action). You can then retrieve the custom variable names and values using getCustomVariable. If there is no custom variable in the requested index, it will return false.

Custom Dimensions are a powerful feature that enable you to track custom values for each visit, and/or each action (page view, outlink, download). This feature is not shipped with Matomo directly but can be installed as a plugin via the Matomo Marketplace (CustomDimensions plugin). Before you can use a Custom Dimension you need to install the plugin and configure at least one dimension, see the Custom Dimensions guide. You will get a numeric ID for each configured Custom Dimension which can be used to set a value for it.

Please note once a Custom Dimension is set, the value will be used for all following tracking requests and may lead toinaccurate results if this is not wanted. For example if you track a page view, the Custom Dimension value will be as well tracked for each following event, outlink, download, etc. within the same page load. Calling this method will not actually trigger a tracking request, instead the values will be sent along with the following tracking requests. To delete a Custom Dimension value after a tracking request call_paq.push(['deleteCustomDimension', customDimensionId]);

It is possible to set a Custom Dimension for one specific action only. If you want to track a Page view, you can send one or more specific Custom Dimension values along with this tracking request as follows:

To define a dimension value pass an object defining one or multiple properties as the last parameter (make sure to specify all parameters as defined in the method, we do not automatically assume the last parameter is customData but instead all parameters that a method defines need to be passed to each method). The property name for a dimension starts with dimension followed by a Custom Dimension ID, for example dimension1. The same behaviour applies for several other methods:

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