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I recommend you to use the MRAA library which is Node.JS compatible. This library has SPI methods that you might find useful for your application, however, there aren't methods for read-only purposes. Actually, in every SPI transfer, there is data that is sent and data that is received so you cannot write or read only. However, you can write your custom methods for only reading data from the SPI slave device. For this, you would have to use the methods provided by the MRAA library, for example the writeByte() method to send data to the SPI bus. In this case, since you are only interested on receive data from the SPI slave device, you can send dummy data and then, get the data returned by the writeByte() method: https://github.com/intel-iot-devkit/mraa
Regarding the SS pin question, you have to use a GPIO in order to select the SPI slave device manually. The GPIO should be set to HIGH to keep the SPI slave device unselected, and set it to LOW to select the device.
Hope you find this information useful.