Diffing lines within a string

[Danielle Greenberg]

Using the example from https://github.com/google/diff-match-patch/wiki/Line-or-Word-Diffs

const text1 = "this is first document\r\n111\r\n222\r\n333\r\n";
const text2 = "this is second document\r\n444\r\n555\r\n666\r\n";

var a = dmp.diff_linesToChars_(text1, text2);
var lineText1 = a.chars1;
var lineText2 = a.chars2;
var lineArray = a.lineArray;
var diffs = dmp.diff_main(lineText1, lineText2, false);
dmp.diff_cleanupSemantic(diffs);
dmp.diff_charsToLines_(diffs, lineArray);
console.log(diffs);

I get:

[Array[2], Array[2]]

1. ▶0: Array[2]
   1.  0: -1
   2.  1: "this is first document 111 222 333 "
2. ▶1: Array[2]
   1.  0: 1
   2.  1: "this is second document 444 555 666 "

It looks like I get the difference per the whole string and I need to compare the lines within the string, the line parts(within the \r\n),
How is that achieved?