Split a text with header

Question

I have a string like this:

&topic1
Lorem ipsum dolor sit amet, consectetur adipiscing elit, 
sed do 
eiusmod tempor incididunt ut 

&topic2
labore et dolore magna aliqua. Ut enim ad minim 
www.example.com/test?id=1&name=abc
veniam, quis nostrud exercitation ullamco lab

&topic3
hello

Each time there is (beginning of line) + & + name + \n, it should be parsed into a new item.

How is the most natural way to parse it this way with Javascript:

[['topic1', 'Lorem ipsum dolor sit amet, consectetur adipiscing elit,\nsed do\neiusmod tempor incididunt ut'],
 ['topic2', 'labore et dolore magna aliqua. Ut enim ad minim\nwww.example.com/test?id=1&name=abc\nveniam, quis nostrud exercitation ullamco lab'],
 ['topic3', 'hello']]

?

I have several problems with this method:

var s = "&topic1\nLorem ipsum dolor sit amet, consectetur adipiscing elit,\nsed do\neiusmod tempor incididunt ut\n\n&topic2\nlabore et dolore magna aliqua. Ut enim ad minim\nwww.example.com/test?id=1&name=abc\nveniam, quis nostrud exercitation ullamco lab\n\n&topic3\nhello";

s.split('&').forEach(function(elt) { console.log(elt.split('\n')[0], elt.split('\n').slice(1)); });

• the first item is empty (this can be removed after, but maybe there's a cleaner way?)

• if & is in the middle of a line (and not beginning) then this code doesn't work

• I'd like the the text after the header title to be in one single string (e.g. Lorem ipsum dolor sit amet, consectetur adipiscing elit,\nsed do\neiusmod tempor incididunt ut), and not split for each \n

How to do a cleaner parsing?

Answer 1

Split by linebreaks first, then join them up until you find a new topic:

var s = "&topic1\nLorem ipsum dolor sit amet, consectetur adipiscing elit,\nsed do\neiusmod tempor incididunt ut\n\n&topic2\nlabore et dolore magna aliqua. Ut enim ad minim\nwww.example.com/test?id=1&name=abc\nveniam, quis nostrud exercitation ullamco lab\n\n&topic3\nhello";

const result = [];
let acc = [];

for(const line of s.split("\n")) {
  if(line[0] === "&") {
    // New topic found
    result.push(acc);
    acc = [line.substr(1), ""];
  } else {
    acc[1] += (acc[1] && "\n") + line;
  }
}

result.push(acc);
result.shift();   // removes the first element from an array and returns that removed element
console.log(result);