Javascript 如何编写if/else函数?
我的购物车有一个功能,当“数据”传递到购物车时,它会显示产品列表,但当没有可用的“数据”时,我希望购物车返回“空购物车”。我可以用if/else语句来实现这一点吗?代码如下Javascript 如何编写if/else函数?,javascript,if-statement,Javascript,If Statement,我的购物车有一个功能,当“数据”传递到购物车时,它会显示产品列表,但当没有可用的“数据”时,我希望购物车返回“空购物车”。我可以用if/else语句来实现这一点吗?代码如下 const propductList = (data) =>{ console.log(data) setTotal(data) } 我想我想做的是这样的事情 const productList = (data) =>{ console.log(data) if (data)
const propductList = (data) =>{
console.log(data)
setTotal(data)
}
我想我想做的是这样的事情
const productList = (data) =>{
console.log(data)
if (data) setTotal
} else return "Empty Cart"
}
完整代码如下:
import React, { useState } from 'react'
import { useDispatch } from 'react-redux';
import {
removeCartItem,
onSuccessBuy
} from '../../../_actions/user_actions';
import UserCardBlock from './Sections/UserCardBlock';
import { Result, Empty, Button } from 'antd';
import Paypal from '../../utils/Paypal';
function CartPage(props) {
const dispatch = useDispatch();
console.log(props)
const [Total, setTotal] = useState(props.location.state.data.price)
const [ShowTotal, setShowTotal] = useState(true)
const [ShowSuccess, setShowSuccess] = useState(false)
const removeFromCart = (productId) => {
dispatch(removeCartItem(productId))
}
const transactionSuccess = (data) => {
dispatch(onSuccessBuy({
cartDetail: props.user.cartDetail,
paymentData: data
}))
.then(response => {
setShowSuccess(true)
setShowTotal(false)
}
)
}
const transactionError = () => {
console.log('Paypal error')
}
const transactionCanceled = () => {
console.log('Transaction canceled')
}
const propductList = (data) =>{
console.log(data)
setTotal(data)
}
return (
<div style={{ width: '85%', margin: '3rem auto' }}>
<h1>My Cart</h1>
<div>
{props.location.state.data &&
<UserCardBlock
productData={props.location.state.data}
removeItem={removeFromCart}
productList={data => propductList(data)}
/>
}
{ShowTotal ? (
<div style={{ marginTop: "3rem" }}>
<h2>Total amount: ${Total * 15} </h2>
</div>
) : ShowSuccess ? (
<Result status="success" title="Successfully Purchased Items" />
) : (
<div
style={{
width: "100%",
display: "flex",
flexDirection: "column",
justifyContent: "center",
}}
>
<br />
<Empty description={false} />
<p>No Items In The Cart</p>
</div>
)}
</div>
{/* Paypal Button */}
{ShowTotal &&
<Paypal
toPay={Total}
onSuccess={transactionSuccess}
transactionError={transactionError}
transactionCanceled={transactionCanceled}
/>
}
</div>
)
}
export default CartPage
import React,{useState}来自“React”
从'react redux'导入{useDispatch};
进口{
移除部件,
onSuccessBuy
}来自“../../../../u操作/用户操作”;
从“./Sections/UserCardBlock”导入UserCardBlock;
从“antd”导入{Result,Empty,Button};
从“../../utils/Paypal”导入Paypal;
功能页(道具){
const dispatch=usedpatch();
控制台日志(道具)
const[Total,setTotal]=useState(props.location.state.data.price)
常量[ShowTotal,setShowTotal]=useState(真)
常量[ShowSuccess,setShowSuccess]=useState(false)
const removeFromCart=(productId)=>{
调度(删除部件(产品ID))
}
const transactionSuccess=(数据)=>{
发送(onSuccessBuy)({
cartDetail:props.user.cartDetail,
paymentData:数据
}))
。然后(响应=>{
setShowSuccess(真)
setShowTotal(假)
}
)
}
常量事务错误=()=>{
console.log('Paypal错误')
}
const TransactionCancelled=()=>{
console.log('事务已取消')
}
常量propductList=(数据)=>{
console.log(数据)
setTotal(数据)
}
返回(
我的手推车
{props.location.state.data&&
propductList(数据)}
/>
}
{ShowTotal(
总额:${Total*15}
):展示成功(
) : (
购物车中没有物品
)}
{/*贝宝按钮*/}
{ShowTotal&&
}
)
}
导出默认CartPage
您可以这样做:
const productList = (data) =>{
if (data) return setTotal(data)
else return "Empty Cart"
}
甚至在三元运算符中更短:
const productList = (data) =>{
return data ? setTotal(data) : 'Empty Cart';
}
甚至更短,直接将三元数作为返回:
const productList = data => data ? setTotal(data) : 'Empty Cart';
什么是setTotal方法?是useState吗?看,是的,是useState谢谢。它并不是说productList现在还没有定义。有没有办法解决这个问题?