问题描述
似乎所有主流浏览器都实现了DOMParser API,以便可以将XML解析为DOM,然后使用XPath,getElementsByTagName等进行查询...
It seems that all major browsers implement the DOMParser API so that XML can be parsed into a DOM and then queried using XPath, getElementsByTagName, etc...
但是,检测解析错误似乎更棘手。 DOMParser.prototype.parseFromString
始终返回有效的DOM。发生解析错误时,返回的DOM包含< parsererror>
元素,但在每个主要浏览器中略有不同。
However, detecting parsing errors seems to be trickier. DOMParser.prototype.parseFromString
always returns a valid DOM. When a parsing error occurs, the returned DOM contains a <parsererror>
element, but it's slightly different in each major browser.
示例JavaScript:
xmlText = '<root xmlns="http://default" xmlns:other="http://other"><child><otherr:grandchild/></child></root>';
parser = new DOMParser();
dom = parser.parseFromString(xmlText, 'text/xml');
console.log((new XMLSerializer()).serializeToString(dom));
Opera中的结果:
DOM的根是< parsererror>
元素。
<?xml version="1.0"?><parsererror xmlns="http://www.mozilla.org/newlayout/xml/parsererror.xml">Error<sourcetext>Unknown source</sourcetext></parsererror>
Firefox中的结果:
DOM的根是< parsererror>
元素。
<?xml-stylesheet href="chrome://global/locale/intl.css" type="text/css"?>
<parsererror xmlns="http://www.mozilla.org/newlayout/xml/parsererror.xml">XML Parsing Error: prefix not bound to a namespace
Location: http://fiddle.jshell.net/_display/
Line Number 1, Column 64:<sourcetext><root xmlns="http://default" xmlns:other="http://other"><child><otherr:grandchild/></child></root>
---------------------------------------------------------------^</sourcetext></parsererror>
Safari中的结果:
< root>
元素正确分析,但包含一个嵌套的< parsererror>
名称空间比Opera和Firefox的< parsererror>
元素。
The <root>
element parses correctly but contains a nested <parsererror>
in a different namespace than Opera and Firefox's <parsererror>
element.
<root xmlns="http://default" xmlns:other="http://other"><parsererror xmlns="http://www.w3.org/1999/xhtml" style="display: block; white-space: pre; border: 2px solid #c77; padding: 0 1em 0 1em; margin: 1em; background-color: #fdd; color: black"><h3>This page contains the following errors:</h3><div style="font-family:monospace;font-size:12px">error on line 1 at column 50: Namespace prefix otherr on grandchild is not defined
</div><h3>Below is a rendering of the page up to the first error.</h3></parsererror><child><otherr:grandchild/></child></root>
我错过了简单的跨浏览器方式检测是否在XML文档中的任何位置发生了解析错误?或者我必须查询不同浏览器可能生成的每个可能的< parsererror>
元素的DOM吗?
推荐答案
这是我提出的最佳解决方案。
This is the best solution I've come up with.
我试图解析故意无效的XML字符串并观察生成的< parsererror>
元素的命名空间。然后,在解析实际的XML时,我可以使用 getElementsByTagNameNS
来检测相同类型的< parsererror>
元素并抛出一个Javascript 错误
。
I attempt to parse a string that is intentionally invalid XML and observe the namespace of the resulting <parsererror>
element. Then, when parsing actual XML, I can use getElementsByTagNameNS
to detect the same kind of <parsererror>
element and throw a Javascript Error
.
// My function that parses a string into an XML DOM, throwing an Error if XML parsing fails
function parseXml(xmlString) {
var parser = new DOMParser();
// attempt to parse the passed-in xml
var dom = parser.parseFromString(xmlString, 'text/xml');
if(isParseError(dom)) {
throw new Error('Error parsing XML');
}
return dom;
}
function isParseError(parsedDocument) {
// parser and parsererrorNS could be cached on startup for efficiency
var parser = new DOMParser(),
errorneousParse = parser.parseFromString('<', 'text/xml'),
parsererrorNS = errorneousParse.getElementsByTagName("parsererror")[0].namespaceURI;
if (parsererrorNS === 'http://www.w3.org/1999/xhtml') {
// In PhantomJS the parseerror element doesn't seem to have a special namespace, so we are just guessing here :(
return parsedDocument.getElementsByTagName("parsererror").length > 0;
}
return parsedDocument.getElementsByTagNameNS(parsererrorNS, 'parsererror').length > 0;
};
请注意,这个解决方案没有'包括Internet Explorer所需的特殊外壳。但是,IE中的内容要简单得多。使用 loadXML
方法解析XML,如果解析成功则返回true或false分别失败。请参阅 http://www.w3schools.com/xml/xml_parser.asp举个例子。
Note that this solution doesn't include the special-casing needed for Internet Explorer. However, things are much more straightforward in IE. XML is parsed with a loadXML
method which returns true or false if parsing succeeded or failed, respectively. See http://www.w3schools.com/xml/xml_parser.asp for an example.
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