How to output unicode character of category Cf?

Question

JavaScript

There are 2 category characters (Cf) ZERO WIDTH JOINER (\u200D) and ZERO WIDTH NON-JOINER (\u200C) - they can be used in variable names if they are not the first characters. What are these symbols, and how to visually see them? https://jsfiddle.net/oo461mkw/5/
And how to distinguish between the categories Cf, Zs, etc. in Unicode . ?

Answer 1

Well, at least they would google for decency.
For example, you have symbols aand b(conditionally). In some languages ​​(c) they are usually written separately, but you need to make a ligature. How to make it? Correct: a ZWJ b. Zero width non-joiner examples:
Let 's say you have characters and . In some languages, they are usually written together ( above ), but you need to write them separately ( ). How to do it? Correct: . Examples Normally, both of these characters are not displayed in any way. Why? Read above.