javascript - If react sets this.id = XXX in the constructor, what is the use of this id?

Question

For example, the id here, why is it defined like this? I see there is no such definition on the Internet, or I can't find it. Please answer. If there is a relevant link, please provide a link. Thank you all

Answer 1

Setting properties in the constructor has no special meaning.
If this writing method is not ES6, it will be easier for you to understand.

function Parent(){
    this.id = +new Date()
}

Parent.prototype.getId = function(){
    console.log(this.id)
}

var  p = new Parent()
p.getId() // 其实这里定义也就是给当前类，定义属性而已。便于后面在当前类里面使用。

Answer 2

The usefulness depends on the person who writes the program. The React component itself does not have this attribute.