预期效果:在<li> </ li>
的基础上,单击index
->取得索引li->在组件this.state.todos
->中共享clock
和index
从数组中选择元素->将Math.random ()
返回的值分配给所选元素--->从数组中选择一个粘合元素->为它分配一个不同的随机值->单击上一个元素--- >显示给我分配的值。
在控制台中,我从selectState
来的未定义。
当我在<li>
之间切换时,索引不会更改。寻求一些建议。
this.sate.selec移至组件“ clock”并分配给this.state.selectTodo
应用
class App extends React.Component {
constructor() {
super();
this.state = {
withInitialTodos: true,
selec: null,
todos: [
{
time: '00:00:10',
description: 'Hello'
},
{
time: '00:00:20',
description: 'World'
}
],
todo: {
'time': '00:00:30',
'description': 'W'
},
selectTodo: {
"times": [{ 'time': '00:00:40' }, { 'time': '00:00:50' }],
"description": " ytytyty",
"id": 3,
"title": "gfgfgfgfgf"
},
saveTodo: {
"time": '03:03:03'
}
};
}
selectTodo = (index) => {
this.setState({
selec: index
})
}
createTodo = (todo) => {
this.setState({
withInitialTodos: false,
todos: [].concat(this.state.todos, this.state.todo),
selectTodo: {
...this.state.selectTodo,
times: [].concat(
this.state.selectTodo.times,
this.state.withInitialTodos ? this.state.todos.map(({ time }) => ({ time })): [],
{
time: this.state.todo.time
}
)
}
});
}
saveTodo = (description) => {
const todo = {
description,
time: '03:03:03'
};
const todos = [].concat(this.state.todos, todo);
this.setState({
todos
});
}
render() {
console.log(this.state.todos);
console.log(this.state.selectTodo);
console.log(this.state.selec);
console.log("sdsd " + this.state.todos[this.state.selec])
return (
<div>
<ul>
{
this.state.todos
.map((todo, index) =>
<Todo
key={index}
index={index}
todo={todo}
selectTodo ={this.selectTodo}
/>
)
}
</ul>
<button onClick={this.createTodo}>Add</button>
<Clock
todos={this.state.todos}
selec={this.state.selec}
/>
</div>
);
}
}
Todo
class Todo extends Component {
render () {
{console.log(this.props.todo)};
return (
<li onClick={()=> this.props.selectTodo(this.props.index)}>
{this.props.todo.description}
</li>
)
}
}
export default Todo;
时钟
class Clock extends Component {
constructor() {
super()
this.state = {
selectTodo: [],
clock: Math.random()
}
}
componentDidMount() {
this.setState({
selectTodo: this.props.todos[this.props.selec]
})
}
render() {
return (
<div>
{this.state.selectTodo = this.state.clock}
</div>
);
}
}
答案 0 :(得分:1)
您的方法不正确。您需要根据组件的行为(应做的事情)来理解和分离组件。状态和道具从上到下传递。牢记这一点将有助于构造组件层次结构。在这种情况下,Todo组件上的selectTodo函数应添加随机时钟值,因为它是该逻辑的最理想位置,并且如果您要显示以前的随机数或时间列表,时钟不需要知道任何信息。您只需要传递所选的组件,它将呈现这些信息。您可以像这样重构代码:
class App extends React.Component {
state = {
todos: [
{ id: 0, times: ["00:00:10"], description: "some desc" },
{ id: 1, times: ["00:00:20"], description: "some desc1" }
],
selectedIndex: null
};
createTodo = todo => {
/**
* Create Todo Logic
*/
}
selectTodo = index => {
let newTodos = [...this.state.todos]
let newTime = Math.random();
newTodos[index].times.push(newTime);
this.setState({todos: newTodos, selectedIndex: index});
}
render() {
<div>
<ul>
{
this.state.todos.map((todo, index) => (
<Todo
key={todo.id}
description={todo}
onSelectTodo={() => this.selectTodo(index)}
/>
))
}
</ul>
<Watch
todo={this.state.todos[this.state.selectedIndex]}
/>
</div>
}
}
如果您对此处没有任何了解,请随时提问。