Create a har file with xhr request only in chrome dev tools
Seems like there is no direct way to filter the requests. What I did was, creating the har file with all the requests and filter that file, then save it again after removing unwanted requests.
There is a entry called entries in the content inside har file. It contains all the requests we have sent in an array. I got the har file content and filtered it using JSONPath expressions.
About JSONPath, JSONPAth evaluator
Expression to filter application/json types : $..entries[?(@.response.content.mimeType == "application/json")]
After that I have replaced the entries array with the one I have filtered in the har file and saved it again. This way you can get a har file with filtered requests. Same way you can filter XHR or any other types using the relevant JSONPath expression