Javascript use match() to select an entire paragraph

Question

I'm trying to extract an entire paragraph from a txt file using JS, then put it to an html element. I've read quite a few posts already and articles, but I can't get the right regex formula. This is an extract of the txt file:

Doing initial required tests

   
   Testing server: xxxxxxxx\yyyyyyyy

      Starting test: Connectivity

         * Active Directory LDAP Services Check
         Determining IP4 connectivity 
         * Active Directory RPC Services Check
         ......................... yyyyyyyy passed test Connectivity



Doing primary tests

What I need to extract is from "Starting test: Connectivity" until "passed test Connectivity". This is the JS code I'm trying:

`

async function getText(file) {
  let dcdiagFile = await fetch(file);
  let dcDiag = await dcdiagFile.text();
  let connectivity = dcDiag.match(/Starting test: Connectivity[\n\r]+$(.*)(/gm) || [];
  document.getElementById("DNS").innerHTML = connectivity;
  console.log(connectivity);
}
getText("./dcdiagreport.txt");

` With my code I only get the first line. I've thought that the wild card would address that, but if I add the word Connectivity as in below:

let connectivity = dcDiag.match(/Starting test: Connectivity[\n\r]+$(.*)Connectivity (/gm) || [];

I don't get anything. In other programming languages I would go with "Text beginning * text ending" the paragraph. But not in JS. It's an intranet internetless servers and preferibly I don't want to download jquery. Vanilla JS only.

The `.` only matches non-line break characters by default, that is, it does not match across lines. To change that behaviour, you have to use the single-line `s` modifier, which treats the whole string as one line with respects to `.`. — oriberu, Dec 08 '22 at 08:35
A different approach to solving this would be to match all consecutive lines that lead with the same horizontal space following your key string. Something like `Starting test: Connectivity[\r\n]+^([ \t]+).*(?:\r?\n\1.*)*`. [Regex101 Demo](https://regex101.com/r/OwoGic/1). — oriberu, Dec 08 '22 at 08:44

score 1 · Accepted Answer · answered Dec 08 '22 at 06:26

You can use a .replace() instead of a .match() to keep only text you need.

You did not specify if you want to include or exclude the keys "Starting test: Connectivity" until "passed test Connectivity". Here is a test with regex1 that includes keys, and regex2 that excludes the keys:

const input = `Doing initial required tests
      Testing server: xxxxxxxx\yyyyyyyy

      Starting test: Connectivity

         * Active Directory LDAP Services Check
         Determining IP4 connectivity 
         * Active Directory RPC Services Check
         ......................... yyyyyyyy passed test Connectivity

Doing primary tests`;

const regex1 = /^.*?(Starting test: Connectivity.*?passed test Connectivity).*$/s;
let connectivity1 = input.replace(regex1, '$1');
console.log(connectivity1);

const regex2 = /^.*?Starting test: Connectivity\s*(.*?)\s*passed test Connectivity.*$/s;
let connectivity2 = input.replace(regex2, '$1');
console.log(connectivity2);

Explanation of regex1:

^ -- anchor at start of text
.*? -- non-greedy scan
( -- start of capture group 1
Starting test: Connectivity -- expect literal text
.*? -- non-greedy scan
passed test Connectivity -- expect literal text
) -- end of capture group 1
.* -- greedy scan
$ -- anchor at end of text
/s -- modifier s to include newlines in .

Explanation of regex2:

similar to regex1, but capture group is more narrow

many thanks Peter! That fixed it! So in JS it is possible as in other languages :) I think I misunderstood what replace() can do... your regex1 does what I need. Thanks again — sigfried, Dec 08 '22 at 09:54

Javascript use match() to select an entire paragraph

1 Answers1