const regex = /\b(\w+)\b(?=(?:(?!\b\1\b).)*\b(\1)\b(?:(?!\b\1\b).)*$)|\b(\w+)\b(?=.*?\b\3\b)/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('\\b(\\w+)\\b(?=(?:(?!\\b\\1\\b).)*\\b(\\1)\\b(?:(?!\\b\\1\\b).)*$)|\\b(\\w+)\\b(?=.*?\\b\\3\\b)', 'gm')
const str = `abc some word abc eee word abc`;
// 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