const regex = /^(?:([*_`]|\*\*|\[){0,1}[a-z]+)(.*)/img;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('^(?:([*_`]|\\*\\*|\\[){0,1}[a-z]+)(.*)', 'img')
const str = `# H1
## H2
### H3
# A First Level Header
## Second Level Header
Now is the time for all good men to come to the aid of their country. This is just a regular paragraph.
The quick brown fox jumped over the lazy dog's back.
*The* quick brown fox jumped over the lazy dog's back.
**The** quick brown fox jumped over the lazy dog's back.
\`The\` quick brown fox jumped over the lazy dog's back.
[The]() quick brown fox jumped over the lazy dog's back.
### Header 3
> This is a blockquote.
>
> This is the second paragraph in the blockquote.
>
> ## This is an H2 in a blockquote`;
// 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