What is the optimal approach for managing server-side data stored as a JavaScript variable?

When dealing with global variables like JSON inserted into a web page server side with PHP, the best way to handle it is up for debate. Options might include leaving it for garbage collection, omitting var initialization and deleting the variable, or simply setting the variable to null and again relying on garbage collection.

Perhaps there are other methods that have not been considered yet. While avoiding the use of AJAX in this scenario is preferred, inserting the variable data directly into the JavaScript code is not feasible due to minification.

EDIT: The reason for this inquiry is the potential size of the data being handled. It prompts questions about the most efficient way to manage it. Additionally, the duration of garbage collection raises uncertainty as to whether it poses a significant concern.

Answer №1

Consider a scenario where the var data = {...} is hardcoded in JavaScript without being sourced from PHP -- where would be the most suitable location to place it?

The recommended practice remains consistent, aiming for the "smallest applicable scope," which could potentially be a global window property, although other architectural designs like modules are generally preferred over this approach.

There are certain issues to be cautious of regarding closures, inadvertent bindings, and managing very large structures (exceeding 100MB+). If the data is only loaded once and no longer needed, it is advisable to allow the object to become inaccessible (through scope termination or null assignment to the variable referencing it) except under specific circumstances:

"We should forget about small efficiencies, say about 97% of the time" -- Knuth

Keep coding happily.

Just remember: using delete does not delete an object entirely, and variables are not automatically garbage collected (although they can maintain object accessibility). Objects are only garbage collected when:

  1. The object is unreachable; and
  2. The garbage collector decides to do so.

Answer №2

If global variables are not being utilized by any function, they will not be recycled by the Garbage Collector. Therefore, it is necessary to use delete data; or delete window.data; when they go out of scope.

Answer №3

If you are required to request the entire chunk of information from the server, there are three options available to you.

1: Utilize the delete method.

2: Store the data in a structured DOM element and retrieve it using JavaScript within a specific scope (which can be garbage collected later), for example,

div id="somefoo" class="invisible-div"><?php getData('somefoo'); ?></div>, then: var somefoo = $('#somefoo').text();

This solution involves parsing and structuring the information before passing it on to JavaScript. Depending on your requirements, this approach may or may not be advantageous.

3: Make an ajax call.

The primary concern is ensuring that the data does not linger unnecessarily after completing its purpose and avoiding memory leaks.

Alternatively, perhaps this is not as significant of a concern. Generally, concerns about garbage collection arise when a large amount of data is returned by getData(). Memory usage issues in JavaScript typically relate to script execution rather than input data. It might be helpful to monitor your script's memory usage using tools like Google Chrome's code profiling tool. For instance, Gmail's memory usage currently stands at 36MB. Determine what constitutes acceptable memory usage limits, assess the data consumption of getData(), and proceed accordingly. It is possible that garbage collection may not even be necessary in your case.

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