Trying to use the DOMParser with node js

I am running into issues when trying to use the DOMParser in my js code. In my code, I retrieve an xml file via xmlhttp.responseText soap response. I want to be able to access its elements in JSON format, so my code looks like:

var xml = new DOMParser();
xml = xml.parseFromString(xmlhttp.responseText, 'text/xml');
var result = xmlToJson(xml);

I get this error message: ReferenceError: DOMParser is not defined

Edit: This link hasn't worked for me because my javascript isn't in the HTML page, as it is a node.js file. JavaScript DOMParser access innerHTML and other properties

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