const regex = /^.+Severity: 20.*\R^.*\R(?![\s\S]*Severity: 20)/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('^.+Severity: 20.*\\R^.*\\R(?![\\s\\S]*Severity: 20)', 'gm')
const str = `2020-01-27 11:12:00.72 Backup Log was backed up. Database: ReportServerTempDB, creation date(time): 2019/05/22(12:31:06), first LSN: 79:1911:1, last LSN: 79:1933:1, number of dump devices: 1, device information: (FILE=1, TYPE=DISK: {'E:\\SQLLogDumps\\ReportServerTempDB_tlog_20200127111200.trn'}). This is an informational message only. No user action is required.
2020-01-27 11:21:47.95 Logon Error: 17806, Severity: 20, State: 14.
2020-01-27 11:21:47.95 Logon Occurrence number one
2020-01-27 11:21:47.95 Logon Error: 18452, Severity: 14, State: 1.
2020-01-27 11:21:47.95 Logon Login failed. The login is from an untrusted domain and cannot be used with Integrated authentication. [CLIENT: 192.168.4.208]
2020-01-27 11:21:47.95 Logon Error: 17806, Severity: 20, State: 14.
2020-01-27 11:21:47.95 Logon Occurrence number two
2020-01-27 11:21:47.95 Logon Error: 18452, Severity: 14, State: 1.
2020-01-27 11:21:47.95 Logon Login failed. The login is from an untrusted domain and cannot be used with Integrated authentication. [CLIENT: 192.168.4.208]`;
// Reset `lastIndex` if this regex is defined globally
// regex.lastIndex = 0;
let m;
while ((m = regex.exec(str)) !== null) {
// This is necessary to avoid infinite loops with zero-width matches
if (m.index === regex.lastIndex) {
regex.lastIndex++;
}
// The result can be accessed through the `m`-variable.
m.forEach((match, groupIndex) => {
console.log(`Found match, group ${groupIndex}: ${match}`);
});
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions