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我试图让加载屏幕在聚合物工作，因为在这个要点看到工作：https://gist.github.com/SlicedSilver/f2e93a5995f84d9cd512获取加载scren与聚合物
的想法很简单：入口点是一个轻量级的HTML文件呈现加载屏幕，其主体包含一个onload回调，一旦呈现轻量级页面，该回调将通过DOM加载Polymer应用程序。
它在桌面浏览器上运行得非常漂亮。在移动浏览器上，filestoload.html永远不会被加载（但也不会引发任何错误），因此加载屏幕只停留在那里，应用程序不会加载。完整的代码如下，但特别注意去这条线：
tag.setAttribute('onload', 'polymerLoader.insertPolymerApplication()');
这onload事件永远不会触发并不会抛出一个错误。我试图通过DOM和适当的事件处理器来捕获它，但无济于事。我甚至试过把它排除所有的完整性检查的JS手中，加入像这样的链接的HTML文件：
<link rel="import" href="/filestoload.html" onload="polymerLoader.insertPolymerApplication()" >
同样的结果 - 显示在桌面上的应用程序，但只显示了在手机上加载屏幕。我刚刚从创意中脱颖而出。任何帮助？
....
这里是轻量级的入口点（的index.html）
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, minimum-scale=1, initial-scale=1, user-scalable=yes">
<link rel="shortcut icon" type="image/png" href="/assets/images/favicon.ico"/>
<title>GreenMaven</title>
<meta name="description" content="greenmaven description">
<script src="assets/js/polymerAppLoader.js"></script>
<style type="text/css">
.loading {
position: fixed;
top: 50%;
left: 50%;
/* bring your own prefixes */
transform: translate(-50%, -50%);
z-index: -500;
display: block;
}
</style>
</head>
<body onload="polymerLoader.loadPolymerApplication()">
<div id="loader" class="loading">
<img src="assets/images/gears.svg" />
</div>
</body>
</html>而这里的加载聚合物应用程序的其余部分JS：
'use strict';
/* global polymerLoader */
/*jshint unused:false*/
/*jshint -W079*/
// This is the normal conditional loader for the Web components Polyfill
if ('registerElement' in document && 'createShadowRoot' in HTMLElement.prototype && 'import' in document.createElement('link') && 'content' in document.createElement('template')) {
// We're using a browser with native WC support!
} else {
// Add web components polyfill...
document.write('<script src="bower_components/webcomponentsjs/webcomponents.lite.js"><\/script>');
}
var polymerLoader = (function() {
// Function for creating a link element and inserting it into the <head> of the html document
function addLinkTag(elementType, address, shim, loadTrigger) {
var tag = document.createElement('link');
tag.rel = elementType;
tag.href = address;
if (shim) {
// add the shim-shadowdom attribute
tag.setAttribute('shim-shadowdom', '');
}
if (loadTrigger) {
// This file needs to be loaded before inserting the Polymer Application
// when finished loading it will call the polymerLoader.insertPolymerApplication() function
tag.setAttribute('onload', 'polymerLoader.insertPolymerApplication()');
expectedCalls++;
}
document.getElementsByTagName('head')[0].appendChild(tag);
}
var pgApploaded = false;
function loadPolymerApplication() {
// Only insert once.
if (!pgApploaded) {
addLinkTag('import', 'filestoload.html', false, true);
pgApploaded = true;
}
}
// Counter variable for insertPolymerApplication() calls
var callCount = 0;
var expectedCalls = 0;
function insertPolymerApplication() {
callCount++;
// Only when callCount >= expectedCalls
// The application is only inserted after all required files have loaded
// for the application to work.
if (callCount >= expectedCalls) {
// here is the html that is inserted when everything is loaded.
document.querySelector('body').innerHTML += '<template is="auto-binding" id="app"><polymer-app id="main-app"></polymer-app></template>';
document.getElementById('loader').style.display = 'none';
}
}
return {
insertPolymerApplication: function() {
insertPolymerApplication();
},
loadPolymerApplication: function() {
loadPolymerApplication();
}
};
})(document);最后，这里是一个已经将通常在聚合物的index.html中找到的链接和脚本文件filestoload.html：
<!doctype html>
<!-- Here is where you put the scripts required by the page, that would normally be -->
<!-- included in the index.html page, you can still use grunt/gulp build functions on these -->
<!-- will be replaced with elements/elements.vulcanized.html -->
<link rel="manifest" href="/manifest.json">
<link rel="import" href="/src/greenmaven-app/greenmaven-app.html">
<link rel="stylesheet" href="assets/css/main.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" integrity="sha384-rwoIResjU2yc3z8GV/NPeZWAv56rSmLldC3R/AZzGRnGxQQKnKkoFVhFQhNUwEyJ" crossorigin="anonymous">
<!-- endreplace-->
<!-- build:js scripts/app.js -->
<script src="properties_base/farmhacker-properties.js"></script>
<!-- endbuild-->
<!-- build:js scripts/thirdparty.js -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>
<script>
$(function() {
$('a[href*="#"]:not([href="#"])').click(function() {
if (location.pathname.replace(/^\//,'') == this.pathname.replace(/^\//,'') && location.hostname == this.hostname) {
var target = $(this.hash);
target = target.length ? target : $('[name=' + this.hash.slice(1) +']');
if (target.length) {
$('html, body').animate({
scrollTop: target.offset().top - $('#navbar').height()
}, 1000);
return false;
}
}
});
});
</script>
<!-- endbuild-->