addItem 函数不起作用,它给出了错误:
警告:遇到两个孩子使用同一把钥匙,
。键应该是唯一的,以便组件保持其状态 跨更新的身份。非唯一的键可能会导致孩子 重复和/或省略 - 该行为不受支持并且可能 未来版本会更改。[object Object]1
addItem() 位于 app.js 中
App.js:
import './App.css';
import React, {Component} from 'react';
import Items from './components/item/items'
import AddItem from './components/addItem/addItem'
import Total from './components/total/total'
class App extends Component {
state = {
items: [
{id:1, product:'Pen', price:2},
{id:2, product:'Book', price:10}
]
}
deleteItem = (id) => {
let items = this.state.items
let i = items.findIndex(item => item.id === id)
items.splice(i, 1)
this.setState({items: items})
}
addItem = () => {
const { items } = this.state;
const id = items.length ? items[items.length - 1] + 1 : 1;
this.setState({ items: [...items, { id }] });
};
addItem2 = (item) => {
this.state.items.length > 0 ? (
item.id = this.state.items[this.state.items.length - 1].id + 1
) : item.id = 1
console.log(item.id)
let items = this.state.items
items.push(item)
this.setState({items: items})
}
render() {
return (
<div className="container">
<h1>Product List React App</h1>
<div className="table">
<Items items={this.state.items} del={this.deleteItem} add={this.addItem}/>
<AddItem add={this.addItem2}/>
<Total items={this.state.items}/>
</div>
</div>
)
}
}
export default App;
items.js:
import React from 'react';
const Items = (props) => {
const {items, del,add} = props;
let length = items.length
const ListItem = length ? (
items.map(item => {
return(
<div key={item.id} className="item">
<p onClick={()=>add(item.id)}>+</p>
<p>{item.product}</p>
<p>{item.price}</p>
<p className="delete" onClick={() => del(item.id)}>×</p>
</div>
)
})
) : (
<div className="text">There are no items, Try to add some.</div>
)
return (
<div>
<div className="header item">
<p>quantity</p>
<p>Product</p>
<p>Price</p>
<p>Edit</p>
</div>
{ListItem}
</div>
)
}
export default Items
total.js:
import React from 'react';
const Total = (props) => {
const {items} = props;
let total = 0
for (let i = 0; i < items.length; i++) {
total += parseFloat(items[i].price)
}
return (
<div>
<p className="text">Total Price: {total}</p>
</div>
)
}
export default Total
您的 addItem 函数中有一个错误。您正在访问整个对象而不是它的 id 属性。
const items = [
{id:1, product:'Pen', price:2},
{id:2, product:'Book', price:10}
];
// your id
const id = items.length ? items[items.length - 1] + 1 : 1;
console.log(id);
// should be
const id2 = items.length ? items[items.length - 1].id + 1 : 1;
console.log(id2);