用正则表达式查找三个或四个逗号分隔的数字

Question

Let's say I have a string *White 4,5,6 LOTE Jr. Service Learning Kick-Off (2017-10-6) and want to find a substring matching the regular expression \\d,\\d,\\d|,\\d , corresponding to any group of 3 or 4 numbers separated by commas, and if the regex isn't present, return an empty string. How can I do this?

Answer 1

 let str = "*White 4,5,6 LOTE Jr. Service Learning Kick-Off (2017-10-6)"; let re = /\\d,\\d,\\d(?:,\\d)?/; let [numbers] = str.match(re) || ['']; console.log(numbers); 

match will return null if it can't find the pattern; || '' || '' will turn that null into an empty string.

Note that I changed your pattern, since yours says "three digits separated by commas - or, a comma and a digit".

If you actually meant numbers as your text says, and not digits, then use /\\d+,\\d+,\\d+(?:,\\d+)?/ for integers; if you need floats or complex numbers, please ask so explicitly (they're quite more... complex).