替换意外删除的新行

Question

I have found a strange behavior with replace and regular expressions that I can not explain. I have a trim function that removes spaces from the start and end of each line of a text:

function trim(str) {
  return str.replace(/^\s+|\s+$/igm, '');
}

But when the text is multi-lined with \\r\\n instead of \\n It also removes the new lines:

console.log(trim('A string \n- with several \n- lines'))
// A string\n- with several\n- lines
console.log(trim('A string \r\n- with several \r\n- lines'))
// A string- with several- lines

Someone can tell me if this is expected behavior that I don't understand or just one of the warts of JavaScript?

EDIT: I don't need to 'fix' the code, I could do it with split + map + trim:

'A string \r\n- with several \r\n- lines'.split('\r\n').map(x => x.trim()).join('\r\n')

I am just curious about the different behaviour in the two examples. If I use match instead of replace I get this:

'A string \r\n- with several \r\n- lines'.match(/^\s+|\s+$/igm)
Array(4) [ " \r", "\n", " \r", "\n" ]
'A string \n- with several \n- lines'.match(/^\s+|\s+$/igm)
Array [ " ", " " ]

WAT?

Answer 1

Change igm to ig . The problem is the modifier m (multiple lines).