How to turn a Javascript Object into a CSS style sheet

I have an object that goes

'buttonProperties' {
    backgroundColor : 'green'
    fontSize : '10px'
}

How would I make the button use those properties using a method like:

Object.keys(buttonProperties).forEach((x) => {
    button.style[x] = buttonProperties[x];
})


const buttonProperties = {
        backgroundcolor: 'green', 
        textSize : '10px'
},

button = document.getElementById('button')

button.addEventListener('click', () => {
  Object.keys(buttonProperties).forEach((x,i) => {
      button.style[x] = buttonProperties[x]
  })
})
<button id = 'button'>Submit</button>