Can i learn JavaScript [without HTML and CSS]?

How JavaScript works?

JavaScript Enables you to create dynamic content, control media, animation and much more. It is the most popural language over stackOverFlow.
Here is the important part, JavaScript works alongside HTML and CSS.
Which means in order to run JavaScript over the webBrowser you need to use HTML otherwise it won't run.

Is it impossible to run JavaScript without HTML?

No, you can use JavaScript Frameworks and Libraries like Vue.js and React.js where you can run JavaScript without using HTML (They just use JSX, JavaScript + XML).
Where React.js is very popular for single page websites and with the help of NODE.js you can work on BackEnd.

Should you skip HTML and CSS and continue with JavaScript?

No, you should learn HTML and CSS alongside JavaScript.
Because HTML and CSS let's you create, Design and style WebElements.
In order to present your idea better and bring your imagination to life you should learn HTML and CSS alongside JavaScript.

Is HTML and CSS hard to learn?

No, HTML and CSS are not hard to learn.
In HTML you have to remember the tag names [we have different tags in HTML to create different Elements like <audio> for creating Audio Element] and in CSS you need to remember the CSS properties [like to change the color of an Element, color:red;].
Remembering everthing all at once is hard, but once you keep using them, you will remember them without any issues.