Top Highlights

• The optional chaining ?. stops the evaluation if the value before ?. is undefined or null and returns undefined.
• As it was said before, the ?. immediately stops (“short-circuits”) the evaluation if the left part doesn’t exist. So, if there are any further function calls or operations to the right of ?., they won’t be made.
• userAdmin.admin?.(); // I am admin userGuest.admin?.(); // nothing happens (no such method)
• The optional chaining ?. has no use on the left side of an assignment.
• let html = document.querySelector('.elem')?.innerHTML; // will be undefined, if there's no element

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