Event on mount

[kelunik]

Thank you for your component! I've implemented an automatic size switch with it. However, I had to manually add a mounted() hook to determine the initial size.

mounted(): void {
   this.handleResize({
      width: (this.$el as HTMLElement).offsetWidth,
      height: (this.$el as HTMLElement).offsetHeight
   });
},

Would you be interested in me submitting a PR to add a property to also fire an event on mount? I'm thinking about appear, just like Vue's <transition />.

[kelunik]

Thanks!