Validate and capture sequence of numbers

Question

I have this string: 16-8-10-20-30-65

The numbers are random and this is just one example.

I need a regular expression that validates that sequence, captures all numbers before 65, including minus signs and excluding the last sign. That is, in the example given, that would be 16-8-10-20-30.

Sequences that end with a hyphen (16-8-) or have more than one hyphen between two numbers (16-8--22) cannot be considered valid. A sequence with a single number (16) can be considered valid. Following link with some tests: https://regex101.com/r/xF6FV/3/tests

What I managed to put together was this:

^([0-9]+-?)+[^-][0-9]*$

That way, the validation works, but I couldn’t capture the data. That’s possible?

Answer 1

You can use:

/([0-9\-]+)\-[0-9]+/

Basically:

• ([0-9\-]+) creates a group with numbers and the hyphen;
• \- will always marry the last hyphen of the expression;
• [0-9]+ will always match the last number of the expression;

Thus, the capture group will return any number and hyphen before the last hyphen. See an example:

const pattern = /([0-9\-]+)\-[0-9]+/;

const tests = [
  "16-8-10-20-30-65",
  "9-2-4-6-8",
  "0-33-25-5667-2-9",
  "12-877-244-796",
  "12",
  "67-28",
  "1---3"
];

for (const test of tests) {
  if (test.match(pattern)) {
    let result = pattern.exec(test)[1];
    console.log(`O teste ${test} retornou: ${result}`);
  } else {
    console.log(`O teste ${test} falhou`);
  }
}

Note that, in this way, an expression with multiple hyphens followed will also be valid.