javascript - Why does the input box input nothing but the value is undefined? ?

Question

Answer 1

You have two-way binding and you have not input anything. Then your printSingle.szLat is undefined.

If you need an empty string for "", you can initialize it

Answer 2

data () {
  return {
    printSingle: {
      szLat: ''
    }
  }
}

Answer 3

The variable is defined, but when there is no value, the value is undefined