const array = ["page=4", "sortOrder=asc", "datePosted=all-time", "sortOrder=desc"];
const match = array.find(value => /^sortOrder=/.test(value));
// match = "sortOrder=asc"
yourString.match(RegExp(/YOUR REGEX/))
const array = ["page=4", "sortOrder=asc", "datePosted=all-time", "sortOrder=desc"];
const match = array.find(value => /^sortOrder=/.test(value));
// match = "sortOrder=asc"