javascript - prop verification in vue2, what is the use of setting default?

Question

html code:

<prop-ver :prop-a="num" :prop-b="num2"></prop-ver>

js code:

var propVer={
    prop:{
        propA:{
            type:Number,
            default:100
        },
        propB:{
            type:Number,
            default:100
        }
    },
    tempalte:'<p>{{propA}}------{{propB}}</p>'
};
new Vue({
    el:'#el',
    data:{
        num:'222',
        num2:222
    },
    components:{
        'prop-ver':propVer
    }
});

The code is as above. "I feel that default is useless and has no prompts or effects.
Solved: I originally thought that the value passed in did not meet the type requirements, and then the default value was used. It turns out to be the default value when there is no value

Answer 1

Make sure it won’t be undefined when you need to use it

Answer 2

The default value, because you passed num and num2 to the two props, the default value is overwritten

Answer 3

Resolved: I thought default was the value passed in if it did not meet the type requirements, and then it was the default value. It turns out to be the default value when there is no value