The left-hand side of an arithmetic operation must be of type ‘any’, ‘number’, ‘bigint’ or an enum type.

props: {
    width: {
      type: Number,
      default: 800,
    },
    height: {
      type: Number,
      default: 300,
    },
    }
    const ratio = computed(() => props.height / props.width)

两种解决方法

其一，声明一个PropsInterface跟props的属性重叠，赋值给setup的props，如果有多个number的props肯定推荐这个

interface CanvasProps {
  width: number
  height: number
}
setup(props:CanvasProps){}

其二用Number强制转换为number

const ratio = computed(() => Number(props.height) / Number(props.width))

或者,就是太丑了
const ratio = computed(() => props.height as number/ (props.width as number))