Question 236997 in Javascript Question posted in
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Javascript – How can I write a regex to extract data preceding and following a specific expression in a text file?

Problem:
I have a logfile containing data and I want to extract the data preceding and following a specific expression. I’ve taken a screenshot of the logfile and highlighted the data I want. You can view the screenshot of the logfile here: logfile.JPG. Since the length, format, and position of the data never change in this line, I am simplifying by showing a specific line from the logfile:

Aug 23 07:25:43 Astrance 125_Heater_1.30.02.0124_d[11421]: 2023-08-23T07:25:43.402421|304|4|1250025|virtual bool CReadTempStep::SPIIsSatisfied():129|Temperatures 39.998318 39.982665 40.167597 40.167027

I am interested in extracting the timestamp at the beginning Aug 23 07:25:43 and the four numbers at the end 39.998318 39.982665 40.167597 40.167027. I’m looking for a single regular expression that can return one match.

My solution so far written in JavaScript:

Regex1, Getting the timestamp (Aug 23 07:25:43):

.*(?= Astrance.*Temperatures)

Regex2, Getting the four numbers (39.998318 39.982665 40.167597 40.167027):

(?<= Astrance.*Temperatures).*

Question:

How can I combine Regex1 and Regex2 into a single regex that returns one match?

Expected answer:

It would be great if somebody provides me a tiny javascript program which returns me all the matches in a list as follows:

MatchList = [
   [ 'Aug 23 07:25:43', '39.998318 39.982665 40.167597 40.167027' ],
   [ 'Aug 23 07:25:45', '39.999999 39.576576 40.676767 40.334444' ],
   [ 'Aug 23 07:25:47', '39.456777 39.734534 40.898899 40.898999' ],
    ...
   ]

Solution (Thanks to the community):

// read local logfile into a variable:

var fs = require("fs");
var logFileString = fs.readFileSync("./sys", "utf-8");

// use regex and write the matches into a list:

const regex = /^(.*?)s*Astrance.*Temperaturess*(.*)/gm;
const matches = Array.from([...logFileString.matchAll(regex)], x => [x[1], x[2]]);

console.log(matches);
Tags:

2

Answers


  1. 0

    Hi here is a working example:

    const string = 'Aug 23 07:25:43 Astrance 125_Heater_1.30.02.0124_d[11421]: 2023-08-23T07:25:43.402421|304|4|1250025|virtual bool CReadTempStep::SPIIsSatisfied():129|Temperatures 39.998318 39.982665 40.167597 40.167027'

const pattern = /(.*(?= Astrance))|((?<=Temperatures ).*)/g


console.log(string.match(pattern)[0])
console.log(string.match(pattern)[2])
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  2. 0

    You can use

    const text = 'Aug 23 07:25:43 Astrance 125_Heater_1.30.02.0124_d[11421]: 2023-08-23T07:25:43.402421|304|4|1250025|virtual bool CReadTempStep::SPIIsSatisfied():129|Temperatures 39.998318 39.982665 40.167597 40.167027';
const regex = /^(.*?)s*Astrance.*Temperaturess*(.*)/gm;
const matches = Array.from([...text.matchAll(regex)], x => [x[1], x[2]]);
console.log(matches);

    See the regex demo. Details:

    • ^ – start of any line (since the m flag is used)
    • (.*?) – Group 1: any zero or more chars other than line break chars as few as possible
    • s* – zero or more whitespaces
    • Astrance.*Temperatures – Astrance, then any zero or more chars other than line break chars as many as possible and then Temperatures
    • s* – zero or more whitespaces
    • (.*) – Group 2: any zero or more chars other than line break chars as many as possible.
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