From Tencent Holdings Ltd. to ByteDance Ltd., China’s internet behemoths have revealed details of their treasured algorithms to Beijing for the first time, an extraordinary move aimed at curtailing data misuse that may jeopardise highly guarded company secrets. The internet watchdog issued a report on Friday listing 30 algorithms used by companies such as Alibaba Group Holding Ltd. and Meituan to collect data on users, make personal recommendations, and offer up content. While the public list did not expose the actual code, it remained unclear how much information internet companies may have supplied to authorities in private. Many online businesses...