from getFillColor: d => [0, 0, 255], // Adjust the fill color as needed we can see that DeckGL is expecting color as an array of numbers but the color scale gives us an rgb value like below. thus i made a wrapper around colorScale and called it getColor you can see what's it doing by building it up step by step with each operation after a dot the last bit converts each value of an array from text to number (using a unary + operation trick) https://www.reddit.com/r/webdev/comments/88kuxk/the_unary_operator_is_a_shortcut_to_convert_a/