const regex = /(?<=<a>)(\s*?<b>([^<]+)<\/b>)(\s*?<b>([^<]+)<\/b>)?(\s*?<b>([^<]+)<\/b>)?(\s*?<b>([^<]+)<\/b>)?/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('(?<=<a>)(\\s*?<b>([^<]+)<\\\/b>)(\\s*?<b>([^<]+)<\\\/b>)?(\\s*?<b>([^<]+)<\\\/b>)?(\\s*?<b>([^<]+)<\\\/b>)?', 'gm')
const str = `<a>
<b>test11</b>
</a>
<a>
<b>test21</b>
<b>test22</b>
</a>
<a>
<b>test31</b>
<b>test32</b>
<b>test33</b>
</a>
<a>
<b>test41</b>
<b>test42</b>
<b>test43</b>
<b>test44</b>
</a>
<c>
<b>test51</b>
<b>test52</b>
</c>`;
// 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