类型错误：无法读取 reactJS 上未定义的属性“map”

Question

我之前不得不做类似的事情（在网格中显示项目），所以我尝试遵循这种模式。我盯着这个看了一会儿，试图找出问题所在。有什么我没有看到的吗？帮助

错误信息

   9 |   console.log(localStorage.getItem("shoppingCart")),
  10 | <div>
  11 |   <Grid container spacing={3}>
> 12 |   {items.map((item) => (
  13 |       <Grid item key={item.VinylID} xs={12} sm={4} >
  14 |           <CartLayout item={item} />
  15 |         {/* <cartLayout

CartItems.js

const CartItems = ({items}) => {
  const classes = useStyles();
  return (
      console.log(localStorage.getItem("shoppingCart")),
    <div>
      <Grid container spacing={3}>
      {items.map((item) => (
          <Grid item key={item.VinylID} xs={12} sm={4} >
              <CartLayout item={item} />
            {/* <cartLayout
              item={lineItem}
              onUpdateCartQty={onUpdateCartQty}
              onRemoveFromCart={onRemoveFromCart}
            /> */}
          </Grid>
        ))}

CartLayout.js

const cartLayout = ({ item }) => {
  const classes = useStyles();
  return (
    <Card className="cart-item">
      {/* <CardMedia/> */}
      <CardContent className={classes.cardContent}>
        <Typography variant="h4"> {item.Name} </Typography>
        <Typography variant="h5"> ${item.VinylPrice} </Typography>
      </CardContent>
      <CardActions className={classes.cartActions}> 
      <div className={classes.buttons}>
          <Button variant="contained" type="button" color="secondary">
              Remove
          </Button>
      </div>
      </CardActions>
    </Card>
  );
};

export default cartLayout;

Cart.js

  constructor(props) {
    super(props);
    this.state = {
      currentData: JSON.parse(localStorage.getItem("shoppingCart")).items,
    };
  }

  render() {
    return (
      <div>
        <CartItems currentData={this.state.currentData}/>
      </div>
    )
  }
}

Answer 1

您需要修复：<CartItems items={this.state.currentData}/>

Answer 2

问题

您将 currentData={this.state.currentData} 作为道具传递，但随后您正在尝试查找项目 const CartItems = ({items}) => {

解决方案

您只需将其更改为 items={this.state.currentData}