Limit more than one linebreak, limit double space, RegEx replace

Question

I'm having trouble limiting a string to prevent multiple spaces and multiple linebreaks. This reformat is gonna happen to an input value before uploading to server.

Ex:

Input:

    i am    a   text
with

little



to no


meaning    asdas

Expected output:

i am a text
with

little

to no

meaning asdas

I googled this but it only helps with linebreaks.

str.replace(/\n\s*\n/g, '\n\n')

Answer 1

Using \s can also match a newline. Instead you can use a negated character class to match a whitespace character without a newline [^\S\n]

You could:

• Trim the string

• Match 2 or more newlines followed by whitespace chars without newlines using ^(?:\n[^\S\n]*){2,} and replace with a single newline

• Match 2 or more whitespace chars without a newline [^\S\n]{2,} and replace with a single space.

const s = `    i am    a   text
with

little



to no


meaning    asdas`;
const result = s.trim()
  .replace(/^(?:\n[^\S\n]*){2,}/gm, "\n")
  .replace(/[^\S\n]{2,}/g, " ");

console.log(result);