Define the embedded data field 'age' at the beginning of the survey flow.
Add moment.js to your survey header.
Add the following JS to a question:
Qualtrics.SurveyEngine.addOnload(function() {
var bdate = moment("${e://Field/BirthDate}","MM/DD/YYYY");
Qualtrics.SurveyEngine.setEmbeddedData('age',moment().diff(bdate,'years'));
});

Thanks so much for your quick response! I tried to follow what you suggested and the "age" field is blank for test respondents/after completing a few test surveys.
1) I added moment.js in the HTML portion of Header under Look & Feel settings. Is that correct location?
2) And, is this what i put when you say "moment.js"?

">https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.21.0/moment.min.js">
3) In survey flow, I added age embedded data field, with "Value will be set from panel or URL", is that accurate or do i need to set the value?
4) Is the format of BirthDate value an issue (i.e., 10/12/1971)? Note: Birthdate is already in survey flow as embedded data field. 

            

    

https://www.qualtrics.com/community/discussion/comment/30748#Comment_30748From what you've written, it appears you've done things correctly. I saw one typo in the code that I corrected above: 'field' should have been 'Field'.

hello I used this code which works fine except for some respondents where age is not calculated. is it that the person did not stay on the question for a long time?

https://www.qualtrics.com/community/discussion/comment/37076#Comment_37076Hard to say without seeing the specifics, but some possible reasons:

1. BirthDate field not populated


2. BirthDate field in wrong format or not a valid date


3. Question containing JS is not displayed (i.e., skipped)



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Strange, however, the date of birth field is present. The same format as the others. And I put the JS on a question posted to all respondents. It's very rare but it happens

https://www.qualtrics.com/community/discussion/comment/37079#Comment_37079If the BirthDates are valid and formatted properly, then perhaps those responses are subverting the JS somehow. You should take a closer look at them; there may other 'suspicious' aspects to them.

HI! I am actually having the same issue for a current survey. For some reason, out of thousands of survey participants there are about 60 people who are missing values in the new "age" field/whose age is not populating. JRKBM were you able to figure out what the issue was?

no sorry I gave up