Some will say things like "Front-end web development using a framework such as ExtJS, React, Vue, or Angular". Neat - which one? I'm happy to work with 1 or maybe 2 of those. Do you mean that you actually use React but you're fine with people who come from some other framework? Or do you mean that you are converting a legacy app from Ext.JS to React so you're hoping the candidate has used both?
Sometimes they'll bury the actual framework in the "Nice to Have" section but it's pretty common for it to be left vague. I think what they're trying to do is widen the pool of applicants, but that strategy seems suboptimal for attracting folks who want to work with a specific tech stack.