Does a scientific book offer something to the author's CV or is it better to write journals/papers?

Question

Does a scientific book offers something to the author's CV or is it better to write journals/papers in order to improve his/her CV?

update (24/06/2023): I am talking about the following:

1. Computer Science/Electrical Engineering/Electronic Engineering/Applied Mathematics
2. By saying scientific book I mean for instance: let's say someone wants to write a book for Algorithms targeting CS undergraduate/graduate university students
3. In order to improve the author's CV targeting let's say to a research position in the future, in a University

Answer 1

This depends very much on the field. In general a scientific book usually contains sufficient material that would result in a number of journal articles.

After clarification:

Textbooks usually do not count towards research goals or for establishing research potential, but are an asset for teaching goals / establishment of teaching potential. A monograph such as a Springer Lecture Note in Mathematics will take the place of several journal articles. For example, in Mathematics, your Ph. D. thesis should give you a number of papers, but if you are lucky and get the chance, a Springer Lecture Note would be a single publication out of your thesis. It is true that some people manage to get a book out of a number of articles, in which case the book would be seen as at least an additional article.

Since contents matter, and quality gets assessed, generic answers are not going to be very accurate.

Answer 2

By saying scientific book I mean for instance: let's say someone wants to write a book for Algorithms targeting CS undergraduate/graduate university students

To get an academic position you need to publish research, which means creating new knowledge. This type of knowledge is usually published in peer reviewed journals, not in books. On occasion, it may be published in book form, in what is usually referred to as a research monograph, which is distinct from the kind of book you are describing, usually referred to as a textbook.

Writing a textbook will have very limited value in helping you launch an academic career. It might be beneficial as something that complements a body of research published in peer reviewed journals, but on its own, it won’t count for much in the disciplines you listed. Moreover, writing a textbook is a very time-consuming task that has a high opportunity cost. If you spend the time it takes to write a textbook, you would be giving up a huge amount of time that would have been available for you to do and publish research. That would put you at a significant competitive disadvantage relative to other people at a similar career stage who are not writing textbooks.

All things considered, for early career researchers writing a textbook is not a good way to advance your academic career.