使用JavaScript从XML字符串中提取值

Question

I am facing the following problem:

I am given a XML string and a message (string) I need a function that can parse the XML string and return an array of ids for the XML tags (id="x") in which the message is present.

I can only use JavaScript for this.

 function getIdByMessage(xml, message) { // problem to solve } var xml = ` <test>blabla</test> <otherstuff>MoreStuff</otherstuff> <message-not-relevant>Not relevant</message-not-relevant> <entry id="4">Function Message<entry> <otherstuff>MoreStuff</otherstuff> <message-not-relevant>Not relevant</message-not-relevant> <entry id="3">Function Message<entry> <otherstuff>MoreStuff</otherstuff> <message-not-relevant>Not relevant</message-not-relevant> ` getIdByMessage(xml, 'Function Message'); // should return [4, 3]; 

Answer 1

First parse the XML into a DOM: see for example Parse XML using JavaScript

Then, on the resulting DOM Document object, execute the XPath expression

//entry[. = 'Function Message']/@id

This will return a set of attribute nodes.

Answer 2

Depending on what might be in the xml you don't necessarily have to parse it. You might get away with just searching it for id="number"

For example:

let matches = xml.match(/id="[\d]+"/gm);
let entryIds = matches.map(m => m.match(/\d+/)[0]));

Or match the whole tag on the first line.