Amazon.com announced better-than-expected second quarter profits on Tuesday, thanks to tighter spending discipline and ever growing electronics sales.

Second-quarter net income surged to $78 million, or 19 cents a share, from $22 million, or 5 cents, a year earlier. Revenue for the internet's largest retailer rose 35 percent to $2.89 billion.

The results beat Wall Street's expectations. Analysts were looking for earnings per share of 16 cents on sales of $2.81 billion, according to Bloomberg.

Shares of Amazon surged more than 12 percent in after-market trading, after tumbling more than 3 percent during the trading day.

Amazon continues to decrease its dependence on books and DVDs, and reported increased sales of electronics and jewelry for the quarter. The company said sales of electronics and other general merchandise rose 55 percent to $970 million, while its media unit, which includes books and CDs, grew 27 percent to $1.83 billion.

But the Seattle-based internet company did have news about one particularly notable book. Amazon said it had received 2.2 million orders for the newest Harry Potter novel prior to the book's July 21 release.

In May, Amazon announced that it would pair up with EMI Group to offer music downloads free of digital rights encryption, positioning itself as a competitor to Apple's iTunes download service.

Amazon also said it expects third quarter revenue between $3 billion and $3.175 billion, which is within the range of analysts' previous forecasts.