I agree that learning the DOM API is an important core skill for web developers. But not that you should avoid using jQuery.
jQuery, or something like, it will be around "forever" because a core problem it solves is inherent to the DOM API.
("forever" actually means for the foreseeable future, projecting out where trends will take us in the future.)
The core problem is, there is no DOM API... there's a collection of DOM APIs which overlap (a lot) but that have various differences from browser to browser and from release to release. Just as importantly to software development, the wholly stable parts aren't really a single API either, but a group of APIs with a lot of duplication and variation in the patterns and idioms used.
For good software of any complexity, you're going to want to build as much of your code as possible in terms of a simple, concise, consistent, stable foundation and the DOM API is not those things. It doesn't have to be jQuery.
(BTW, I'm mainly talking about application-level code here. For utilities, plugins or other lighter-weight libraries, NOT requiring a separate library is a significant advantage. And your DOM access may be limited and well-defined so that a vanilla approach isn't burdensome.)
jQuery, or something like, it will be around "forever" because a core problem it solves is inherent to the DOM API.
("forever" actually means for the foreseeable future, projecting out where trends will take us in the future.)
The core problem is, there is no DOM API... there's a collection of DOM APIs which overlap (a lot) but that have various differences from browser to browser and from release to release. Just as importantly to software development, the wholly stable parts aren't really a single API either, but a group of APIs with a lot of duplication and variation in the patterns and idioms used.
For good software of any complexity, you're going to want to build as much of your code as possible in terms of a simple, concise, consistent, stable foundation and the DOM API is not those things. It doesn't have to be jQuery.
(BTW, I'm mainly talking about application-level code here. For utilities, plugins or other lighter-weight libraries, NOT requiring a separate library is a significant advantage. And your DOM access may be limited and well-defined so that a vanilla approach isn't burdensome.)