Parse XML with javascript from url

Helo, I'm a beginner in javascript,

For a project, I need to parse an XML File with JS, I'm using Jquery.

How can I open xml by its url please?

var xml = "Fichier.xml",
xmlDoc = $.parseXML( xml ),
$xml = $( xmlDoc ),

I have an error at this line xmlDoc = $.parseXML( xml ), : Invalid XML : test.xml (error 0)