In modern software, including web applications, context-dependent behavior is one of the most important features. Context-oriented programming (COP) is a suitable programming technique for developing such software. However, we often need to work on handling parameter values in layers. This problem means inconvenience in setting parameters by each layer. We call it “layer parameter problem.” Especially front-end web applications use a component-based approach with a DOM tree, making the layer parameter problem more complicated because they cannot handle COPs in class-in-layer and layer-in-class models. We propose ReactCOP, an implementation of an idea that applies COP to React, one of the front-end web application libraries. ReactCOP solves the parameter problem on a layer-in-component model. As the solution to this problem, we present Layer Parameter Management that dynamically switches values in a variable within a layer. In this paper, we propose ReactCOP with Layer Parameter Management. Finally, we investigate our proposed approach through two case studies.