I'm afraid I have never used Vue.js. Maybe worth asking on stackoverflow. I will leave this open in the hope some in the future can add some suggestions here.

I have already sloved this problem. Thank you all the same.

Can you share the fix here, in case anyone else has the same issue.

Just sharing for anyone looking to use this library in a Vue project (the Vue part in this case will be the page contained in the iFrame).

You need to put the iframeResizer.contentWindow.min.js into your src folder then include these lines in your main.js file:

import * as Resize from './path/to/iframeResizer.contentWindow.min.js'
Vue.use(Resize)

Got it woking doing this way.