javascript Split string with regex

Question

I have the following 2 string which I supposed to split according to delimiter: '/' or "/*"

my code:

var move = "1/2/13/14";
var results = move.split(new RegExp("[/\*?]"));

results are GOOD:

["1","2","13","14"]

BUT, for the next example:

var move = "1/*2/13/*14";
var results = move.split(new RegExp("[/\*?]"));

I get BAD results:

["1","","2","13","","14"]

Why?? How can I modify it to work correctly?

Thank you!

• epascarello: What do you expect the outcome to be? Just like the first?

Answer 1

You can just make * optional after /:

"1/*2/13/*14".split( /\/\*?/ );
["1", "2", "13", "14"]
"1/2/13/14".split( /\/\*?/ );
["1", "2", "13", "14"]

Answer 2

By using [], you are creating a character class, which means "any one of these symbols". This means your regex is looking for the literal characters /, * (needlessly escaped in char class), or ? for splitting. The * and ? do not take on their meta functionality inside the character class.

The regex you'll want is /\/\*?/ (as a regex literal), or with the constructor new RegExp("/\\*?"). You do not need the character class.

Answer 3

You are having problems because you are grouping the characters with the brackets .[ and ]). In a regular expression, those characters will allow any of the characters within the group to be matched.

If you remove them like this: var results = move.split(new RegExp("/\\*?"));, you should get the results that you want.

Answer 4

This one helps:

move.split(new RegExp("[/][*]?"));

• collapsar: @eldarerathis just for the record, a single \ in the character class with * would have no impact, as it is interpreted as the escape symbol. it would take a double backslash to cause trouble ( move.split(/[/][\\*]?/); nb: the RegExp constructor takes a string as its argument, thus a double escape would apply, thus it takes new RegExp("[/][\\\\*]?") to fail). Anyway, you are perfectly right that the escaping inside the character class is superfluous.