Which is it really? You are confusing me :P
> i want this job.
This is what makes you the best candidate. Show them you're really interested. Don't falter.
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Long story short: You'll be fine, and here's why:
That job posting you saw is a generic HR post. Typical "big net hiring" - HR throws very broad job post to attract people. If the company was really serious in finding "experts", they'd post the specific technologies used. If I were looking for an expert, I'd put in "Looking for front-end dev, specifically React and SASS". That would already imply that you know a lot of the front end to end up using SASS and React. Without this, you'll probably end up doing front-end design, layouting, a few dabs of JS here and there, nothing really serious.
There's usually an implicit message with job postings. "a year" is not enough to become an expert in the technology, but is enough to experience handling the kind of work. By that, it means you know how to handle the management, the clients, the sudden changes of schedules, the policies, the extra hours of work, deadlines and so forth. A few months is all it needs to drive away someone who can't take it. If you managed several years already, congratulations!