Whenever a web page tries to load, your browser looks for directions within the site’s code, which almost always include JavaScript tags. The tags control what content is delivered to each visitor and also impact a website’s speed in regard to loading times. JavaScript has two forms, “Synchronous JavaScript” and “Asynchronous JavaScript.” We will describe the second form here, but please read through our “Synchronous JavaScript” description to better compare the two.

“Asynchronous JavaScript” is read by your browser in a way that allows multiple commands to initiate at the same time, without requiring a previous command to complete before moving on to the next action. This form of JavaScript is much preferred by the web design community, as it allows for faster load times and prevents pages from being hung while waiting for a single action to complete.

The most common JavaScript form is “Synchronous JavaScript,” which is read by your browser as its name suggests: in a synchronous order. Logically, this may sound great, but in reality, it means slower loading times as the next action can’t begin until the previous action has completed. Slower loading times may cause companies visitor loyalty and revenue gains in a fraction of a second.

Implementation of Asynchronous JavaScript has not been as wide-spread as desired due to a JavaScript-specific construct, “document.write,” which requires synchronous loading. This construct is used for inserting various items into a website and is almost always present in JavaScript code.

Alternatives are being worked on in tandem, varying between manufacturer solutions (for example, HTML5) and tag-writing library solutions (tools that convert synchronous scripts into asynchronous scripts). Until an ideal solution is reached, website developers should test their websites’ load times frequently and ensure their performance speeds are maximized to the best of their ability.

Dynamic Yield supports both ways.

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