setTimeout

Question

Consider the following HTML:

<html>
    <head></head>
    <body>
        <input type="text" onblur="window.setTimeout('document.title += 2;', 0);" />
        <input type="button" onclick="document.title += 1" />
    </body>
</html>

[Demo with 0 delay, 100ms delay, 150ms delay]

And the following steps:

User enters the input (focus).
User clicks the button.

Now, the events would occur on the following order:

Input Text blur event.
Button click event.

Testing this on all reachable browsers I get:

document.title = '21' //Expected behavior

But! On production browser (Windows XP + IE 7), I get:

document.title = '12' //Unexpected behavior

I also tried simulating it in IE 7 mode on my local machine (IE 10), couldn't reproduce it tho.

This is obviously a simplified example of the problem I'm having. Otherwise I could simply get rid of the setTimeout.

In the real scenario, the setTimeout call is actually being made by a third party script library (ASP.NET Dev Express Components).

Apart from the actual solution to this problem (which I think I can handle), what explanation could be applied to this behavior?

Update:

Using the expression new Date().getTime() to get the time of each step executed by the browser. It happens as follows:

1387369361417 //document.title += 1
1387369361433 //document.title += 2

svidgen · Accepted Answer

Two possibilities:

Your click (mousedown + mouseup) is finishing before IE7's minimum timeout period.
The mousedown status is blocking scripts. Events must wait until other scripts and user-interactions are finished before they fire. And given the history of script-UI weirdness/terribleness in IE, I'd bet the mousedown "begins a user interaction" and the mouesup "ends user interaction". Load this up in IE7:
```
<input type="text" onblur="window.setTimeout('output(2));', 0); output(3);" />
<input type="button" onclick="output(1);" />
```
http://jsfiddle.net/sMcE3/

… and after you'd focus()'d on the text field, click that button real slow-like. I'm guessing you'll see 312. (As opposed to the 321 that any half-decent browser will show.)

setTimeout - Weird behavior

Tags:

javascript

Mateus Schneiders

1 Answers

svidgen

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