const regex = /(?:is|are) ([a-zA-Z0-9- ]+?) if\b/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('(?:is|are) ([a-zA-Z0-9- ]+?) if\\b', 'gm')
const str = `A relation is well-defined if each element in the domain is assigned to a unique element in the range.
invertible if and only
A mapping is invertible on sth if and only if it is both one-to-one and onto
infinite set, we give a specific proof for the smallest integer being considered, followed by a generic argument showing that
mathematical induction. Instead of attempting to verify a statement about some subset S of the positive integers N on a case-by-case basis, an impossible task if S is an infinite set, we give a specific proof for the smallest integer being considered, followed by a generic argument showing that if the statement holds for a given case, then it must also hold for the next case in the sequence.`;
// 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