Text to HTML conversion.

paragraphs.js

var split_p_and_br = s => s.trim().split(/\n\n/).map(s => s.replace(/\n/g, '<br />'))
var split_p = s => s.trim().split(/\n\n/).map(s => s.replace(/\n/g, ' '))

var join_p = p => p.join('</p><p>')

var fin = t => `<p>${t}</p>`

var a = `
hello

multi
line
string

oh
yeah
`

var with_breaks = fin(join_p(split_p_and_br(a)))
var without_breaks = fin(join_p(split_p(a)))