javaScript function - why my default argument fails?

Question

My Javascript function leads my console to return me :

TypeError: style is null

Here the snippet:

Answer 1

Rename your style variable into styles and then instead of having null as your first argument when you invoke styling, use undefined:

const styles = {
  one: 1,
  two: 2,
  three: 3
}

function styling(style = styles, ...ruleSetStock) {

  return ruleSetStock.map(ruleSet => {
    console.log(ruleSet)
    return style[ruleSet]
  })
}

console.log(styling(undefined, "one", "two", "three"))
// one
// two
// three
// [1, 2, 3]