All three major indexes have rallied since the start of the year, and we're getting closer and closer to a new bull market. That's great news for growth stocks because they are often the ones to benefit in an optimistic environment that favors expansion. In fact, many growth stocks have taken off this year for that very reason. But that doesn't mean you can't find a deal on these sorts of stocks right now.

Some top-quality growth stocks have completely missed out on the rally. Others climbed in the first half of the year but recently have dipped. That's the case of Chewy (CHWY 2.99%), down more than 50% so far this year, and CRISPR Therapeutics (CRSP 0.34%), which slipped 16% over the past three months.

Let's take a closer look at these bargain growth stocks that you'll want to buy hand over fist right now.

1. Chewy

If you're a pet parent, you might know Chewy well. The company is an online retailer of everything from pet food and toys to pet insurance and medicine. Chewy makes it easy to take care of your furry or not-so-furry friends by offering Autoship -- a system that automatically reorders and ships your favorite products right to your door.

Autoship keeps customers coming back, as seen in Chewy's earnings reports. In the most recent quarter, Autoship sales represented more than 75% of Chewy's net sales. This kind of customer loyalty is a good sign, offering a reason to be optimistic about future sales. Another positive sign is the fact that Chewy's active customers are increasing their spending on the website. In the quarter, net sales per active customer rose by more than 14%.

And even in a difficult economic context, Chewy has managed to grow. The company reached a big milestone recently, reporting its first annual profit last year.

But growth doesn't stop here. Chewy plans to expand into Canada -- its first international location -- in the third quarter of this year. Importantly, Chewy sees the market share and profit opportunity as similar to those of the U.S. So this could be a major driver of growth for Chewy in the years to come.

As you can see, Chewy has reported a lot of good news over the past several months, but the stock performance hasn't reflected any of it. The shares now trade for 30 times forward earnings estimates, which offers long-term investors the opportunity to buy them at a reasonable price, then potentially win big over time.

2. CRISPR Therapeutics

CRISPR Therapeutics is heading for its biggest moment yet. The gene editing specialist is awaiting regulatory decisions on what may become its very first commercialized product. The U.S. Food and Drug Administration (FDA) is set to decide on exa-cel for sickle cell disease in December and on exa-cel for beta thalassemia in March. The company and partner Vertex Pharmaceuticals also submitted the candidate for regulatory approval in the U.K. and Europe.

Options to address these particular blood disorders are limited, and exa-cel has been designed as a one-time curative treatment -- so doctors and patients could rush out to give the product a try. In fact, analysts predict it will generate blockbuster revenue.

So, even though CRISPR shares profit with Vertex -- 40% for CRISPR and 60% for Vertex -- this represents a big step forward. An approval also would represent a vote of confidence for the gene editing technology CRISPR uses throughout its pipeline.

And speaking of the pipeline, CRISPR may not be far from commercializing a second product. The company is studying an immuno-oncology candidate in a phase 2 trial that could support a regulatory submission.

Meanwhile, CRISPR also may generate revenue by licensing its gene editing technology to other companies. For example, Vertex recently bought nonexclusive rights to use CRISPR's gene editing in its type 1 diabetes program. This involved a $100 million up-front payment and potential milestone and royalty payments.

CRISPR shares now are trading much lower than they were a few years ago -- when we had a lot less visibility on the future. Yes, an exa-cel approval may be baked in at today's level, but I don't believe the potential product's full sales potential is -- and that's why long-term investors could reap the rewards if they pick up shares of this gene editing player today.