Why does String.match( / \d*/ ) return an empty string?

Question

Can someone help me to understand why using \\d* returns an array containing an empty string, whereas using \\d+ returns [\"100\"] (as expected). I get why the \\d+ works, b

Answer 1

/\d*/

means "match against 0 or more numbers starting from the beginning of the string".

When you start the beginning for your string, it immediately hits a non-number and can't go any further. Yet this is considered a successful match because "0 or more".

You can try either "1 or more" via

/\d+/

or you can tell it to match "0 or more" from the end of the string:

/\d*$/

Find all in Python

In Python, there is the findall() method which returns all parts of the string your regular expression matched against.

re.findall(r'\d*', 'one to 100')
# => ['', '', '', '', '', '', '', '100', '']

.match() in JavaScript, returns only the first match, which would be the first element in the above array.