What does \d in Javascript regex do?

Question

What does \d do in this example?

/Chapter (\d+)\.\d*/

Answer 1

In what context?

In a regular expression, it matches a digit (0-9).

Edit, according to your comment:

It matches any string starting with Chapter, followed by digits, then a dot, then a number of digits. Like Chapter 1.0 and Chapter 12.01.

Answer 2

In a regex it means digits 0-9

\d Digits 0 through 9 /H\d/ matches "H3"

Answer 3

If it is in a regular expression (match or replace or split) or a /.../ string then it probably means match any digit 0-9. Please provide the code you see it in so we can be sure.