Check for XML errors using JavaScript
Question: How do I syntax-check my XML in modern browsers (anything but IE)?
I've seen a page on W3Schools which includes an XML syntax-checker. I don't know how it works, but I'd like to know how I may achieve the same behavior.
I've already performed many searches on the matter (with no success), and I've tried using the DOM Parser to check if my XML is "well-formed" (also with no success).
var xml = 'Caleb'; var parser = new DOMParser(); v开发者_如何学Goar doc = parser.parseFromString(xml, 'text/xml');
I expect the parser to tell me I have an XML syntax error (i.e. an unclosed name tag). However, it always returns an XML DOM object, as if there were no errors at all.
To summarize, I would like to know how I can automatically check the syntax of an XML document using JavaScript.
P.S. Is there any way I can validate an XML document against a DTD (using JS, and not IE)?
Edit: Here is a more concise example, from MDN:
var xmlString = '<a id="a"><b id="b">hey!</b></a>';
var domParser = new DOMParser();
var dom = domParser.parseFromString(xmlString, 'text/xml');
// print the name of the root element or error message
dump(dom.documentElement.nodeName == 'parsererror' ? 'error while parsing' : dom.documentElement.nodeName);
NoBugs answer above did not work with a current chrome for me. I suggest:
var sMyString = "<a id=\"a\"><b id=\"b\">hey!<\/b><\/a>";
var oParser = new DOMParser();
var oDOM = oParser.parseFromString(sMyString, "text/xml");
dump(oDOM.getElementsByTagName('parsererror').length ?
(new XMLSerializer()).serializeToString(oDOM) : "all good"
);
You can also use the package fast-xml-parser, this package have a validate check for xml files:
import { validate, parse } from 'fast-xml-parser';
if( validate(xmlData) === true) {
var jsonObj = parse(xmlData,options);
}
Just F12 to enter developer mode and check the source there you can then search validateXML and you are to locate a very long complete XML checker for your reference.
I am using react and stuff using the DOMParser to present the error message as:
handleXmlCheck = () => {
const { fileContent } = this.state;
const parser = new window.DOMParser();
const theDom = parser.parseFromString(fileContent, 'application/xml');
if (theDom.getElementsByTagName('parsererror').length > 0) {
showErrorMessage(theDom.getElementsByTagName('parsererror')[0].getElementsByTagName('div')[0].innerHTML);
} else {
showSuccessMessage('Valid Xml');
}
}
Basic xml validator in javscript. This code may not valid for advance xml but basic xml.
function xmlValidator(xml){
// var xml = "<note><to>Tove</to><from>Jani</from><heading>Reminder</heading><body>Don't forget me this weekend!</body></note>";
while(xml.indexOf('<') != -1){
var sub = xml.substring(xml.indexOf('<'), xml.indexOf('>')+1);
var value = xml.substring(xml.indexOf('<')+1, xml.indexOf('>'));
var endTag = '</'+value+'>';
if(xml.indexOf(endTag) != -1){
// console.log('xml is valid');
// break;
}else{
console.log('xml is in invalid');
break;
}
xml = xml.replace(sub, '');
xml = xml.replace(endTag, '');
console.log(xml);
console.log(sub+' '+value+' '+endTag);
}
}
var xml = "<note><to>Tove</to><from>Jani</from><heading>Reminder</heading><body>Don't forget me this weekend!</body></note>";
xmlValidator(xml);
/**
* Check if the input is a valid XML file.
* @param xmlStr The input to be parsed.
* @returns If the input is invalid, this returns an XMLDocument explaining the problem.
* If the input is valid, this return undefined.
*/
export function xmlIsInvalid(xmlStr : string) : HTMLElement | undefined {
const parser = new DOMParser();
const dom = parser.parseFromString(xmlStr, "application/xml");
// https://developer.mozilla.org/en-US/docs/Web/API/DOMParser/parseFromString
// says that parseFromString() will throw an error if the input is invalid.
//
// https://developer.mozilla.org/en-US/docs/Web/Guide/Parsing_and_serializing_XML
// says dom.documentElement.nodeName == "parsererror" will be true of the input
// is invalid.
//
// Neither of those is true when I tested it in Chrome. Nothing is thrown.
// If the input is "" I get:
// dom.documentElement.nodeName returns "html",
// doc.documentElement.firstElementChild.nodeName returns "body" and
// doc.documentElement.firstElementChild.firstElementChild.nodeName = "parsererror".
//
// It seems that the parsererror can move around. It looks like it's trying to
// create as much of the XML tree as it can, then it inserts parsererror whenever
// and wherever it gets stuck. It sometimes generates additional XML after the
// parsererror, so .lastElementChild might not find the problem.
//
// In case of an error the <parsererror> element will be an instance of
// HTMLElement. A valid XML document can include an element with name name
// "parsererror", however it will NOT be an instance of HTMLElement.
//
// getElementsByTagName('parsererror') might be faster than querySelectorAll().
for (const element of Array.from(dom.querySelectorAll("parsererror"))) {
if (element instanceof HTMLElement) {
// Found the error.
return element;
}
}
// No errors found.
return;
}
(Technically that's TypeScript. Remove : string and : HTMLElement | undefined to make it JavaScript.)
加载中,请稍侯......
精彩评论