As the key technology of Web 2.0, mashup is to access, process various data sources and then create new value-added and highly customizable services. And business logic description language is very important to mashup. This paper proposes a solution to create lightweight mashup services based on JavaScript language. First, mashup architecture based on SOA is generally introduced. Then design and implementation mashup services based on JavaScript language is discussed in detail, including mashup server framework, JavaScript Engine to evaluate JavaScript file, JavaScript host objects used to access data sources, and deploy of JavaScript files as Services. In addition, a concrete example of mashup services creation using JavaScript is given. Finally, performance analyses of this new approach have been conducted to prove it an effective solution.