In the worst case, you can do something along the lines of [file1, file2, file3].join(';\n') albeit if you're using any kind of post-processing tool, like

In the worst case, you can do something along the lines of [file1, file2, file3].join(';\n') albeit if you're using any kind of post-processing tool, like UglifyJS or Google's Closure compiler, then everything just works, as these tools actually parse JavaScript. There's usually no need to explicitly concatenate the code prior to minification or other processing.