const regex = /^(?=\# ?\d+\.)/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('^(?=\\# ?\\d+\\.)', 'gm')
const str = `# This is a comment <-beacuse it starts at the begining of the file
# This is a comment <- see above
# 1. Item one <- not a comment because it starts with 1.
# Description of Item 1 <- not a comment as it is after a line that starts with a number
data point 1
data point 2
data point etc
3 <-- represents number of data points under Item one
# 2. Item two <-- not a comment
# Description of item 2 <-- not a comment
data point 1
data point ..
data point 100
100
#3. Item three <--- not a comment
# Item three description
0`;
// 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