英文:
How to create a method from another method?
问题
我正在尝试找到告诉TypeScript编译器一个方法将在运行时创建的最佳做法。
interface Todo { /* ... */ }
export class TodoModel {
todos: Todo[] = [];
constructor() {
//...
}
bindTodoListChanged(callback: (todos: Todo[]) => void) {
this.onTodoListChanged = callback
}
_save(todos: Todo[]) {
this.onTodoListChanged(todos)
localStorage.setItem('todos', JSON.stringify(todos))
}
}
我当前收到以下错误：
Property 'onTodoListChanged' does not exist on type 'TodoModel'. Did you mean 'bindTodoListChanged'?
我认为使用断言 ! 可能有所帮助
bindTodoListChanged(callback: (todos: Todo[]) => void) {
this.onTodoListChanged! = callback
}
_commit(todos: Todo[]) {
this.onTodoListChanged(todos)
localStorage.setItem('todos', JSON.stringify(todos))
}
我还尝试过
onTodoListChanged(todos: Todo[]): void
bindTodoListChanged(callback: (todos: Todo[]) => void) {
this.onTodoListChanged! = callback
}
_commit(todos: Todo[]) {
this.onTodoListChanged(todos)
localStorage.setItem('todos', JSON.stringify(todos))
}
这产生了以下错误：
Function implementation name must be 'onTodoListChanged'.
最后，我尝试在我的 tsconfig.json 中使用 "strictPropertyInitialization": false，但我更喜欢不必更改配置。
英文:
I'm trying to to find the best practice for telling the ts compiler that a method will be created at run time.
interface Todo { /* ... */ }
export class TodoModel {
todos: Todo[] = [];
constructor() {
//...
}
bindTodoListChanged(callback : (todos: Todo[]) => void) {
this.onTodoListChanged = callback
}
_save(todos: Todo[]) {
this.onTodoListChanged(todos)
localStorage.setItem('todos', JSON.stringify(todos))
}
}
I currently receive this error:
Property 'onTodoListChanged' does not exist on type 'TodoModel'. Did you mean 'bindTodoListChanged'?
I thought using an assert ! would help
bindTodoListChanged(callback : (todos: Todo[]) => void) {
this.onTodoListChanged! = callback
}
_commit(todos: Todo[]) {
this.onTodoListChanged(todos)
localStorage.setItem('todos', JSON.stringify(todos))
}
I've also tried
onTodoListChanged(todos: Todo[]): void
bindTodoListChanged(callback : (todos: Todo[]) => void) {
this.onTodoListChanged! = callback
}
_commit(todos: Todo[]) {
this.onTodoListChanged(todos)
localStorage.setItem('todos', JSON.stringify(todos))
}
Which produced this error:
Function implementation name must be 'onTodoListChanged'.
Lastly, I've tried "strictPropertyInitialization": false in my tsconfig.json But I would prefer to not have to alter the config.
答案1
得分: 3
你需要声明 class field onTodoListChanged，可能是一个 optional property，因为它可能不存在：
class TodoModel {
/* ⋯ */
onTodoListChanged?: (todos: Todo[]) => void
/* ⋯ */
}
这将阻止编译器抱怨 onTodoListChanged 不存在：
bindTodoListChanged(callback: (todos: Todo[]) => void) {
this.onTodoListChanged = callback // okay
}
因为它是可选的，你需要在调用它之前检查它是否未定义；最简单的方法可能是使用 optional chaining operator (?.)：
_save(todos: Todo[]) {
this.onTodoListChanged?.(todos) // okay
localStorage.setItem('todos', JSON.stringify(todos))
}
英文:
You need to declare the class field onTodoListChanged, presumably as an optional property because it might not exist:
class TodoModel {
/* ⋯ */
onTodoListChanged?: (todos: Todo[]) => void
/* ⋯ */
}
This will stop the compiler from complaining that onTodoListChanged doesn't exist:
bindTodoListChanged(callback: (todos: Todo[]) => void) {
this.onTodoListChanged = callback // okay
}
Because it's optional, you'll have to check that it's not undefined before calling it; the easiest way to do that is probably to use the optional chaining operator (?.):
_save(todos: Todo[]) {
this.onTodoListChanged?.(todos) // okay
localStorage.setItem('todos', JSON.stringify(todos))
}
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