[英]Access properties from derived class
abstract class Base {
constructor() {
console.log(this.components)
}
components = ['']
}
class Child extends Base {
components = ['button', 'text']
}
const f = new Child()
Running this code, I get 运行这段代码,我得到
['']
But I would rather like to get 但我想得到
['button', 'text']
from the derived Class. 从派生的类。 Reason I want to do this: I want to validate the "components"-property, which the user defined in the Child. 我想这样做的原因:我想验证用户在Child中定义的“组件”属性。 Is it not possible ? 不可能吗?
The components property is being set just after the constructor in the base class has been called: 在调用基类中的构造函数之后,立即设置components属性:
abstract class Base {
constructor() {
console.log(this.components)
}
components = ['']
}
class Child extends Base {
constructor() {
// inherited components from base = ['']
super() // Call base constructor
// this.components = ['button', 'text']
}
components = ['button', 'text']
}
const f = new Child()
You need to wait for the base constructor to synchronously complete, before you can access the new values - ie. 您需要等待基本构造函数同步完成,然后才能访问新值-即。 by using setTimeout
: 通过使用setTimeout
:
constructor() {
setTimeout(() => console.log(this.components))
}
Ideally you should pass the components as parameters: 理想情况下,您应该将组件作为参数传递:
abstract class Base {
constructor(public components = ['']) {
console.log(components)
}
}
class Child extends Base {
constructor() {
super(['button', 'text'])
// this.components = ['button', 'text']
}
}
const f = new Child()
try this: 尝试这个:
abstract class Base {
constructor(components) {
console.log(components)
}
}
class Child extends Base {
constructor() {
super(['button', 'text'])
}
}
const f = new Child()
or 要么
abstract class Base {
constructor(components) {
console.log(components)
}
}
class Child extends Base {
}
const f = new Child(['button', 'text'])
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