For some files such as HTML, CSS, JavaScript files, Eclipse uses language servers so to provide support for code completion, syntax error reporting, etc. The language servers require the presence of Node.js on the PATH of the system where Eclipse is running; otherwise, when it is missing from the PATH, an error is reported when a file with an extension configured to use a language server is opened for first time:
Could not find node.js. This will result in editors missing key features.Please make sure node.js is installed and that your PATH environment variable contains the location to the `node` executable.
To work around the error, and to use the full features of the language servers in Eclipse, Node.js must be installed on the system and the path to node.exe (Windows), or node (UNIX) should be on the PATH.