typescript - What is the meaning of question mark in expressions in Angular 2?

Question

What does values?.listArray mean here? Specifically I am interested in the question mark.

[inputValue] = "values?.listArray"

Answer 1

Edit

Since the original answer, Ecmascript, and Typescript (in 3.7) have both added the ?. (called the optional chaining operator) operator. See the PR for details.

Original answer

This is not a Typescript operator. Angular 2 has a safe navigation operator in templates.

values?.listArray

is equivalent to

values != null ? values.listArray: null

More info here and here