CODEWITHSUNDEEP
javascript
Taylor Lopez
Taylor Lopez

Reputation: 863

Javascript Rule of thumb for delay length while using setTimeout() to allow a "loading" popup to appear

I'm using the setTimeout() function in javascript to allow a popup that says "loading" to be shown while I'm parsing some xml data. I found that at small enough delay values (below 10ms) it doesn't have time to show it before the browser freezes for a moment to do the actual work. At 50ms, it has plenty of time, but I don't know how well this will translate to other systems. Is there some sort of "rule of thumb" that would dictate the amount of delay necessary to ensure a visual update without causing unnecessary delay?

Obviously, it'll depend on the machine on which the code is running etc., but I just wanted to know if there was anything out there that would give a little more insight than my guesswork.

The basic code structure is:

showLoadPopup();

var t = setTimeout(function()
{
    parseXML(); // real work
    hideLoadPopup();
}, delayTime);

Thanks!

UPDATE: Turns out that parsing XML is not something that Web Workers can usually do since they don't have access to the DOM or the document etc. So, in order to accomplish this, I actually found a different article here on Stack Overflow about parsing XML inside a Web Worker. Check out the page here.

By serializing my XML object into a string, I can then pass it into the Web Worker through a message post, and then, using the JavaScript-only XML parser that I found in the aforementioned link, turn it back into an XML object within the Web Worker, do the parsing needed, and then pass back the desired text as a string without making the browser hang at all.

Upvotes: 1

Views: 161

Answers (2)

Taylor Lopez
Taylor Lopez

Reputation: 863

There appears to be no "rule-of-thumb" for this question simply because it was not the best solution for the problem. Using alternative methods to do the real meat of the work was the real solution, not using a setTimeout() call to allow for visual update to the page.

Given options were:

Thanks for the advice, all.

Upvotes: 0

Josiah Ruddell
Josiah Ruddell

Reputation: 29831

Ideally you would not ever have to parse something on the client side that actually causes the browser to hang. I would look into moving this to an ajax request that pulls part of the parsed xml (child nodes as JSON), or look at using Web Workers or a client side asynchronous option.

Upvotes: 1

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