const regex = /(?<=class=")\s?btn(?=\s?(?:btn-)?(?:mini|small|large)?\s?")/g;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('(?<=class=")\\s?btn(?=\\s?(?:btn-)?(?:mini|small|large)?\\s?")', 'g')
const str = `<button class="btn btn-mini" />
<button class="btn btn-small" />
<button class="btn btn-large"/>
<button class="btn"/>
<button class="btn "/>
<button class=" btn"/>
<button class="btn btn-mini btn-primary" />
<button class="btn btn-small btn-success" />
<button class="btn btn-large btn-info"/>
<button class="btn btn-error"/>`;
// 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