我试图访问iframe中的元素，而.find（）无法选择任何元素。如果我访问.contents[0]我会得到整个文档，但如果我尝试.find( "*" )或任何其他选择器它返回一个空对象。两个html文件都在同一个文件夹中。
var iframe_all = $('#iframe_vote').contents().find( "*" )
var iframe_document = $('#iframe_vote').contents()[0]
console.log(iframe_all)
console.log(iframe_document)
结果：
Object { length: 0, prevObject: {…} }
HTMLDocument file:///c:/Users/piero/OneDrive/Documents/Visual%20Studio%202017/Projects/marketPredictions/marketPredictions/vote.html
URL: "file:///c:/Users/piero/OneDrive/Documents/Visual%20Studio%202017/Projects/marketPredictions/marketPredictions/vote.html"
activeElement: <body>
alinkColor: ""
all: HTMLAllCollection { 0: html.no-js, 1: head, 2: meta, … }
anchors: HTMLCollection []
applets: NodeList []
baseURI: "file:///c:/Users/piero/OneDrive/Documents/Visual%20Studio%202017/Projects/marketPredictions/marketPredictions/vote.html"
bgColor: ""
body: <body>
characterSet: "UTF-8"
charset: "UTF-8"
HTML：
<!DOCTYPE html>
<!--[if lt IE 7]> <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
<!--[if IE 7]> <html class="no-js lt-ie9 lt-ie8"> <![endif]-->
<!--[if IE 8]> <html class="no-js lt-ie9"> <![endif]-->
<!--[if gt IE 8]><!--> <html class="no-js"> <!--<![endif]-->
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title></title>
<meta name="description" content="">
<meta name="viewport" content="width=device-width, initial-scale=1">
<script type="text/javascript" src="jquery.js"></script>
<link rel="stylesheet" type="text/css" href="css\vote.css">
</head>
<body>
<a id = 'btnPlus' href="#plus">
<span class="bg" id="plus"></span>
<span class="symbol"></span>
</a>
<a class="button minus" id = 'btnMinus'href="#minus">
<span class="bg" id="minus"></span>
<span class="symbol"></span>
</a>
<span class="cancel">
<a href="#">Clear</a>
</span>
</body>
</html>
你需要设置一个服务器环境来处理iframe，file:///不是一个有效的域，会导致跨域验证问题
请记住，两个页面都需要托管在同一个域/服务器上
这是一个安全措施，这里有一些更多的信息：https://blog.chromium.org/2008/12/security-in-depth-local-web-pages.html