(Node.js) Regular Expression with Capture Groups

See more Regular Expressions Examples

Note: Chilkat uses PCRE2. See PCRE2 Regular Expressions
Also see: PCRE2 Performance

Demonstrates the following PCRE2 regular expression:

See the sample code below.

Name:\s+(\w+)\s+(\w+),\s+Email:\s+(\S+)

And apply it to this string:

Name: John Smith, Email: john.smith@example.com

Regex Components Explained

Part	Meaning	Matched Text
"Name:"	Matches the literal text "Name:"	"Name:"
"\s+"	Matches one or more whitespace characters (spaces, tabs, etc.)	(space)
"(\w+)"	Capture Group 1: One or more word characters ("a-zA-Z0-9_")	"John"
"\s+"	More whitespace	(space)
"(\w+)"	Capture Group 2: Another word (the last name)	"Smith"
","	A literal comma	","
"\s+"	Whitespace again	(space)
"Email:"	Matches the literal "Email:"	"Email:"
"\s+"	Whitespace	(space)
"(\S+)"	Capture Group 3: One or more non-whitespace characters	"john.smith@example.com"

Matches for Your Example String

String:

"Name: John Smith, Email: john.smith@example.com"

Regex Match Groups:

Group	Captured Value
Group 1	"John"
Group 2	"Smith"
Group 3	"john.smith@example.com"

Notes on Character Classes

\w matches [a-zA-Z0-9_] — so it doesn’t include punctuation like a period.
\S matches any non-whitespace character, so it’s good for capturing an email.

Note: This example requires Chilkat v11.1.0 or greater.

For more information, see https://www.chilkatsoft.com/chilkat_pcre2.asp

Install Chilkat for Node.js and Electron using npm at

Chilkat npm packages for Node.js
Chilkat npm packages for Electron
on Windows, Linux, MacOS

var os = require('os');
if (os.platform() == 'win32') {  
  var chilkat = require('@chilkat/ck-node23-win64'); 
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node23-linux-arm');
    } else if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node23-linux-arm64');
    } else {
        var chilkat = require('@chilkat/ck-node23-linux-x64');
    }
} else if (os.platform() == 'darwin') {
  var chilkat = require('@chilkat/ck-node23-mac-universal');
}

function chilkatExample() {

    var success = false;

    var subject = "Name: John Smith, Email: john.smith@example.com";
    var pattern = "Name:\\s+(\\w+)\\s+(\\w+),\\s+Email:\\s+(\\S+)";

    var sb = new chilkat.StringBuilder();
    sb.Append(subject);

    var json = new chilkat.JsonObject();
    json.EmitCompact = false;

    var timeoutMs = 2000;
    var numMatches = sb.RegexMatch(pattern,json,timeoutMs);
    if (numMatches < 0) {
        // Probably an error in the regular expression.
        // Suggestion: Use AI to help create and/or diagnose regular expressions.
        console.log(sb.LastErrorText);
        return;
    }

    // Examine the matches:
    console.log(json.Emit());

    // This is the JSON with the match information.
    // See the JSON parsing code below to get the matched capture group values.

    // Important:  Capture group 0 always contains the entire match — that is, the portion of the input string that matches the full regular expression.

    // {
    //   "match": [
    //     {
    //       "group": [
    //         {
    //           "cap": "Name: John Smith, Email: john.smith@example.com",
    //           "idx": 0,
    //           "len": 47
    //         },
    //         {
    //           "cap": "John",
    //           "idx": 6,
    //           "len": 4
    //         },
    //         {
    //           "cap": "Smith",
    //           "idx": 11,
    //           "len": 5
    //         },
    //         {
    //           "cap": "john.smith@example.com",
    //           "idx": 25,
    //           "len": 22
    //         }
    //       ]
    //     }
    //   ]
    // }

    var cap;
    var i = 0;
    var matchCount = json.SizeOfArray("match");
    while (i < matchCount) {
        console.log("Match " + (i+1) + ":");
        json.I = i;
        var j = 0;
        var numCaptureGroups = json.SizeOfArray("match[i].group");
        while (j < numCaptureGroups) {
            json.J = j;
            cap = json.StringOf("match[i].group[j].cap");
            console.log(j + ": " + cap);
            j = j+1;
        }

        i = i+1;
    }

    // Capture group 0 always contains the entire match — that is, the portion of the input string that matches the full regular expression.

    // Output

    // Match 1:
    // 0: Name: John Smith, Email: john.smith@example.com
    // 1: John
    // 2: Smith
    // 3: john.smith@example.com

}

chilkatExample();