Example of fill bgColor cell in excel4node

Basically what you can do with the package in its current state is the following:

fill: {
    type: 'pattern', // the only one implemented so far.
    patternType: 'solid', // most common.
    fgColor: '2172d7', // you can add two extra characters to serve as alpha, i.e. '2172d7aa'.
    // bgColor: 'ffffff' // bgColor only applies on patternTypes other than solid.
}

Note that the background color of your cell will be the foreground color (fgColor) of the fill property. It sounds confusing, but it makes sense when you understand that the fill property have patterns that use more than one color, hence the property having foreground and background colors.

The 'solid' patternType is probably what you're looking for, but there are others, such as 'darkDown', 'darkHorizontal', 'lightGrid', and etc, as can be seen here: excel4node/fillPattern.js