You can use following two approach to access attribute value from event object-
Approach 1 – Retrieve using standard Attribute: Here we can use name attribute. We access the attribute value using event.target.{attribute name}. Check printNameAttribute method in below code which retrieves value from Name attribute.
Approach 2 – Retrieve using Custom Attribute: Here we use data attribute. We access the attribute value using event.target.dataset.{data attribute name}. Check printDataAttribute method in below code which retrieves value from Data attribute. Data Attribute name is here target-id which is user defined. In javascript you will refer that as targetId.
<!DOCTYPE html> <html> <body> <button data-target-id='This is Data Attribute Example' onclick="printDataAttribute(event)" >Test Data Attribute</button> <button name='This is Name Attribute Example' onclick="printNameAttribute(event)" >Test Name Attribute</button> <p id="demo"></p> <script> function printDataAttribute(event) { document.getElementById("demo").innerHTML = event.target.dataset.targetId; } function printNameAttribute(event) { document.getElementById("demo").innerHTML = event.target.name; } </script> </body> </html>
Note: The same way of retrieving value using event can be used in Lighting Web Component as well.
SFDC Arjuna 