关于JavaScript是否会阻塞图片加载

<?php
//1.js.php
sleep(5);
file_put_contents("tmp.txt", __FILE__.'->'.__LINE__.' ->' .date("Ymd H:i:s")."\r\n", FILE_APPEND);
?>
console.log("1.js");

<?php
//2.js.php
sleep(3);
file_put_contents("tmp.txt", __FILE__.'->'.__LINE__.' ->' .date("Ymd H:i:s")."\r\n", FILE_APPEND);
?>
console.log("2.js");

<?php
//img.pgp
file_put_contents("tmp.txt", __FILE__.'->'.__LINE__.' ->' .date("Ymd H:i:s")."\r\n", FILE_APPEND);
?>

用不同浏览器访问t.html:

<script  language="javascript" src="1.js.php"></script>
<script  language="javascript" src="2.js.php"></script>
<img src="img.php" />

日志：

firefox 29.0.1

C:\D\OA_SVN\PHP\kkdian_pv\www\main\2.js.php->3 ->20140523 03:34:17

C:\D\OA_SVN\PHP\kkdian_pv\www\main\1.js.php->3 ->20140523 03:34:19

C:\D\OA_SVN\PHP\kkdian_pv\www\main\img.php->3 ->20140523 03:34:19

ie 10

C:\D\OA_SVN\PHP\kkdian_pv\www\main\img.php->3 ->20140523 03:33:20

C:\D\OA_SVN\PHP\kkdian_pv\www\main\2.js.php->3 ->20140523 03:33:23

C:\D\OA_SVN\PHP\kkdian_pv\www\main\1.js.php->3 ->20140523 03:33:25

chrome 34.0.1847.137 m

C:\D\OA_SVN\PHP\kkdian_pv\www\main\img.php->3 ->20140523 03:34:46

C:\D\OA_SVN\PHP\kkdian_pv\www\main\2.js.php->3 ->20140523 03:34:49

C:\D\OA_SVN\PHP\kkdian_pv\www\main\1.js.php->3 ->20140523 03:34:51

C:\D\OA_SVN\PHP\kkdian_pv\www\main\img.php->3 ->20140523 03:34:51

safari 5.1.7 windows

C:\D\OA_SVN\PHP\kkdian_pv\www\main\2.js.php->3 ->20140523 03:36:50

C:\D\OA_SVN\PHP\kkdian_pv\www\main\1.js.php->3 ->20140523 03:36:52

C:\D\OA_SVN\PHP\kkdian_pv\www\main\img.php->3 ->20140523 03:36:52

结论：

ie chrome不会阻塞图片加载，firefox safari会阻塞图片加载；但他们都不会阻塞js加载，js加载是多线程的。