情况是：
Javascript boomerang.js用作客户端网速的测试，问题是html内容是由浏览器执行而不是等待回旋结果。但是需要回旋镖结果，因为html内容有一些变化。
如何在boomernag.js产生结果之前不执行html内容？
编辑：在谷歌搜索之后没有可能阻止浏览器在javascript完成之前不加载html内容，因为boomerang不会阻止这个内容，甚至我们在BOOMR.init中设置autorun：false而不是通过BOOMR.page_ready调用它（）;在任何地方。它是本机javascript异步行为。所以我们不能使用以下代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel='stylesheet' type='text/css' media='all' href='css/style.css' />
<link rel='stylesheet' type='text/css' media='all' href='css/colorbox.css' />
<script type="text/javascript" src="js/speedtest/boomerang.min.js"></script>
<script>
BOOMR.init({ beacon_url: "http://www.zzz.xx", user_ip: '10.0.0.1', site_domain: "http://www.zzz.xx", BW: { nruns: 3, base_url: 'http://www.zzz.xx/test_images/', cookie: 'SPEED-test'}});
</script>
<script type="text/javascript" src="js/preload.js"></script>
preload.js只是检查cookie，如果存在则不再进行测试，如果不存在，请通过BOOMR.subscribe运行speedtest
function getCookie(cname)
{
var name = cname + "=";
var ca = document.cookie.split(';');
for(var i=0; i<ca.length; i++)
{
var c = ca[i].trim();
if (c.indexOf(name)==0) return c.substring(name.length,c.length);
}
return "";
}
var version_set=getCookie("speedtest_version_set");
if (version_set == "low"){
$(document).ready(website_init_low);
} else if (version_set == "high"){
$(document).ready(website_init_high);
} else {
BOOMR.subscribe('before_beacon', function(o) {
if(o.bw) {
netspeed = Math.abs(parseInt(o.bw*8/1024));
var netspeed_limit = 5000;
if (netspeed < netspeed_limit) {
document.cookie="speedtest_version_set = low";
$(document).ready(website_init_low);
} else {
document.cookie="speedtest_version_set = high";
$(document).ready(website_init_high);
}
}
});
}
我们唯一能做的就是制作单独的index.php文件，然后调用index_low.html或index_high.html，如下所示：
<?php
echo "<script type='text/javascript' src='js/speedtest/boomerang.min.js'></script>";
echo "<script type='text/javascript' src='js/speedtest/bw.js'></script>";
echo "<script type='text/javascript'>BOOMR.init({ beacon_url: 'xxx', user_ip: '10.0.0.1', site_domain: 'xxxxxx', autorun: false, BW: { nruns: 3, base_url: 'js/speedtest/test_images/', cookie: 'xxxxx'}})</script>";
echo "<script type='text/javascript'>
function getCookie(cname) //read cookie by javascript
{
var name = cname + '=';
var ca = document.cookie.split(';');
for(var i=0; i<ca.length; i++)
{
if(typeof String.prototype.trim !== 'function') { //IE bug fix -IE not support trim();
String.prototype.trim = function() {
return this.replace(/^\s+|\s+$/g, '');
}
}
var c = ca[i].trim(); //IE bug fix -IE not support trim();
if (c.indexOf(name)==0) return c.substring(name.length,c.length);
}
return '';
}
var netspeed;
var netspeed_limit = 5000;
var version_set=getCookie('speedtest_version_set');
if (version_set == 'low'){
window.location = 'index_low.html'
} else if (version_set == 'high'){
window.location = 'index_hight.html'
} else{
BOOMR.page_ready(); //fire BOOMR only from this place
BOOMR.subscribe('before_beacon', function(o) {
if(o.bw) {
netspeed = Math.abs(parseInt(o.bw*8/1024));
if (netspeed < netspeed_limit) {
document.cookie='speedtest_version_set = low';
window.location = 'index_low.html'
} else {
document.cookie='speedtest_version_set = high';
window.location = 'index_high.html'
}
}
});
}
</script>";
?>
当然，更好的方法是在PHP中使用$ _COOKIE变量检查cookie，而不是通过javascript检查。