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Google PageSpeed Insight shows some SellerDeck scripts as blocking scripts

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    Google PageSpeed Insight shows some SellerDeck scripts as blocking scripts

    Google Pagespeed gives a warning for SellerDeck sites about blocking scripts and CSS. Typical messages include:
    Eliminate render-blocking JavaScript and CSS in above-the-fold content
    Your page has 3 blocking script resources and 2 blocking CSS resources. This causes a delay in rendering your page.
    None of the above-the-fold content on your page could be rendered without waiting for the following resources to load. Try to defer or asynchronously load blocking resources, or inline the critical portions of those resources directly in the HTML.
    Remove render-blocking JavaScript:

    The suggested solution for these issues is to load the JavaScript and CSS after the page has been rendered. However, this assumes that the CSS and Javascript required to render the page initially is embedded in the page; or that it's OK to change the page after the initial rendering.

    SellerDeck pages, particularly if they are responsive, have complex CSS to render them correctly on all devices and display sizes. In addition filtered pages have a large script to implement filtering in the page. Other areas that are dependent on scripts are sliders, carousels, stock level, dynamic prices, dynamic choices and sequential option selection. It is infeasible to embed all of these scripts in the page as they would swell the content of every page.

    In addition, experience has shown that delays in rendering or running scripts can cause confusion for the customer. For example, a delay in setting up product options according to stock levels might mean that a customer has an opportunity to order an out-of-stock product before the script executes.

    Therefore SellerDeck's policy is to not delay loading of SellerDeck's JavaScript and CSS.

    If your site is properly configured then only the first page that is loaded will see any delay due to downloading JavaScript/CSS. There are many actions which can be taken to minimise the impact:
    • ensure that your JavaScript is properly minified into as few files as possible
    • ensure that compressed data transfer is enabled
    • check that proper browser caching is enabled by your site

    Note that other scripts, like those for Google Analytics, Twitter, Facebook and Live Chat are loaded dynamically. Typically this is a little snippet of JavaScript embedded in the page which causes the larger script to be downloaded after the page is rendered. In our experience this can cause problems as they may delay essential rendering of other page elements, so some care has to be taken with them. For example, it makes sense to delay live chat for a few seconds as it isn't essential for that to be seen as soon as possible, and it normally doesn't impact the page layout in any way. If you want help with any of these actions then you should contact your site designer, or contact SellerDeck about consultancy work.