2- To Calculate Age
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--->> BUILD -->DOCTYPE --> SEARCH "EMPLOYEE"
--->> BUILD -->CLIENT SCRIPT -->ADD NEW --> DOCTYPE=EMPLOYEE-->ENTER CODE
//RENAME "age" TO YOUR CUSTOM FIELD NAME.//
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frappe.ui.form.on('Employee', {
    date_of_birth: function(frm) {
        if (frm.doc.date_of_birth) {
            var birthDate = new Date(frm.doc.date_of_birth);
            var today = new Date();
            var ageInMilliseconds = today - birthDate;
            var ageInYears = Math.floor(ageInMilliseconds / (365.25 * 24 * 60 * 60 * 1000));
            frm.set_value('age', ageInYears);
        }
    }
});