英文:
Uncaught TypeError: Cannot read properties of undefined (reading 'length') in the submit form
问题
我想在按下"Agregar"按钮时在控制台中显示我的待办事项,但我得到以下错误:Uncaught TypeError: Cannot read properties of undefined (reading 'length'),你能帮我吗?
TodoApp.jsx:
import { useReducer } from "react";
import { todoReducer } from "./todoReducer";
import { TodoList } from "./TodoList";
import { TodoAdd } from "./TodoAdd";
export const TodoApp = () => {
const initialState = [
{
id: new Date().getTime(),
description: "recolectar piedra de alma",
done: false,
},
{
id: new Date().getTime() * 3,
description: "recolectar piedra de infinito",
done: false,
},
];
const [todos, dispatchTodo] = useReducer(todoReducer, initialState);
const handleNewTodo = (todo) => {
console.log({ todo });
};
return (
<>
<h1>
TodoApp (10) <small>Pendientes 2</small>
</h1>
<hr />
<div className="row">
<div className="col-7">
<TodoList todos={todos} />
</div>
</div>
<div className="col-5">
<h4>Agregar TODO</h4>
<hr />
<TodoAdd onNewTodo={handleNewTodo} />
</div>
</>
);
};
TodoAdd.jsx:
import { useForm } from '../hooks/useForm';
export const TodoAdd = ({ onNewTodo }) => {
const { description, onInputChange, onResetForm } = useForm({
description: ''
});
const onFormSubmit = (event) => {
event.preventDefault();
if (description.length <= 1) return;
const newTodo = {
id: new Date().getTime(),
done: false,
description: description,
};
onNewTodo(newTodo);
onResetForm();
}
return (
<form onSubmit={onFormSubmit}>
<input
type="text"
placeholder="¿Qué hay que hacer?"
className="form-control"
name="description"
value={description}
onChange={onInputChange}
/>
<button
type="submit"
className="btn btn-outline-primary mt-1"
>
Agregar
</button>
</form>
)
}
从我理解的情况来看,description属性似乎从未传递给表单,因为当使用.length时不返回任何数字,所以属性没有被填充。但我真的不知道该怎么做。
英文:
I want to show my todo in the console when pressing the "Agregar" button, but I get the following error: Uncaught TypeError: Cannot read properties of undefined (reading 'length'), could you give me a hand?
TodoApp.jsx
import { useReducer } from "react"
import { todoReducer } from "./todoReducer";
import { TodoList } from "./TodoList";
import { TodoAdd } from "./TodoAdd";
export const TodoApp = () => {
const initialState = [
{
id: new Date().getTime(),
description: "recolectar piedra de alma",
done: false,
},
{
id: new Date().getTime() * 3,
description: "recolectar piedra de infinito",
done: false,
},
];
const [todos, dispatchTodo] = useReducer(todoReducer, initialState);
const handleNewTodo = (todo) => {
console.log({todo});
};
return (
<>
<h1>
TodoApp (10) <small>Pendientes 2</small>
</h1>
<hr />
<div className="row">
<div className="col-7">
<TodoList todos={todos} />
</div>
</div>
<div className="col-5">
<h4>Agregar TODO</h4>
<hr />
<TodoAdd onNewTodo={handleNewTodo} />
</div>
</>
);
};
TodoAdd.jsx:
import { useForm } from '../hooks/useForm';
export const TodoAdd = ({ onNewTodo }) => {
const { description, onInputChange, onResetForm } = useForm({
description: ''
});
const onFormSubmit = ( event ) => {
event.preventDefault();
if ( description.length <= 1 ) return;
const newTodo = {
id: new Date().getTime(),
done: false,
description: description,
}
onNewTodo(newTodo);
onResetForm();
}
return (
<form onSubmit={ onFormSubmit }>
<input
type="text"
placeholder="¿Qué hay que hacer?"
className="form-control"
name="description"
value={ description }
onChange={ onInputChange }
/>
<button
type="submit"
className="btn btn-outline-primary mt-1"
>
Agregar
</button>
</form>
)
}
From what I understand, the description never arrives as a property to the form, since when using the .length it does not return any number, so that is why the property is not fulfilled, but I really don't know what to do
答案1
得分: 0
你是否从useForm
中返回description
?按照以下方式定义useForm
可能会解决问题。
export const useForm = ({ description }) => {
const [newDescription, setNewDescription] = useState(description);
const onInputChange = (e) => {
setNewDescription(e.target.value);
};
const onResetForm = () => {
setNewDescription("");
};
return { description: newDescription, onInputChange, onResetForm };
};
英文:
Do you return description
from useForm
?
Define useForm
as follows may solve the problem.
export const useForm = ({ description }) => {
const [newDescription, setNewDescription] = useState(description);
const onInputChange = (e) => {
setNewDescription(e.target.value);
};
const onResetForm = () => {
setNewDescription("");
};
return { description: newDescription, onInputChange, onResetForm };
};
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