Modifying new/edit item form to add ECMA script on save click

Question

I have a requirement of doing some complex calculations based on the multi lookup values selected in the form while creating an item. I can't use a calculated column nor SharePoint designer as they don't support calculations based on lookup values. I'm looking at no code option and hence no event handlers. I'm planning to use ECMA script to do the same when the item is saved. One approach might be to add a content editor to the new/edit form pages, but I'm looking at some better ways of doing.

1. Is there a way to hookup ECMA script to the save button and call the javascript function to update a field with the calculated value?
2. Can I do the update operation asynchronously in the new item form after the item is saved?

Thanks

Answer 1

PreSaveAction, will let you do processing on item click with your own custom logic.

It executes your code and returns true and saves or returns false and prevents the item from being saved until the data is corrected.