NEXTJS 条件语句在地图内部不起作用

Question

当我编译这段代码时，它给我一个错误，说我没有正确关闭 a 标签。

当我删除以下代码中的条件语句时，它可以正常工作：

{nid[index] != undefined ? (  
 <a target= "_blank" rel="noreferrer" href={polygonURL + Cont[index] + "/" + nid[index]}>
) : (
 <a target= "_blank" rel="noreferrer" href={unkpolygonURL + Cont[index]}>

)}

import styles from "../styles/Home.module.css";
import React, { useEffect, useState, useRef } from "react";
import { useAddress, useMetamask, useDisconnect } from "@thirdweb-dev/react";
import Spinner from "./Spinner";

export default function NFT() {

  const address = useAddress();
  let image = "";
let total = 0;
  const [title, setTitle] = useState([]);
  const [Img, setImg] = useState([]);
  const [Cont, setCont] = useState([]);
  const [nid, setNid] = useState([]);
const[totalNFT, setTotalNFT] = useState(0);

let page = "";

const polygonURL = "https://opensea.io/assets/matic/";
const unkpolygonURL = "https://opensea.io/assets?search[query]=";



  const getPolygonNFT = async (str) => {

    // const api = 'https://eth-mainnet.alchemyapi.io/v2/demo/getNFTs/?owner=0xfae46f94ee7b2acb497cecaff6cff17f621c693d';
    const api = `https://polygon-mainnet.g.alchemyapi.io/v2/demo/getNFTs/?owner=` + str;
    const response = await fetch(api);
    const data = await response.json();
    
    console.log(data);
    let total = data.totalCount;
    let firsttotal = data.ownedNfts.length;
    setTotalNFT(data.ownedNfts.length);
    // setPage(data.pageKey);
    let page = data.pageKey;


    for (var i = 0; i < firsttotal; i++){
      setImg(oldArray => [...oldArray, data.ownedNfts[i].media[0].gateway]);
      setTitle(oldArray => [...oldArray, data.ownedNfts[i].metadata.name]);
      setCont(oldArray => [...oldArray, data.ownedNfts[i].contract.address]);
    setNid(oldArray => [...oldArray, data.ownedNfts[i].metadata.edition])
    
    } 

    let j = true;
    let count = 0;

    while (j){

       
      
if (page != undefined){



  const api = `https://polygon-mainnet.g.alchemyapi.io/v2/demo/getNFTs/?owner=` + str + `&pageKey=` + page;

  const response = await fetch(api);
  const data = await response.json();
console.log(data)

 page = data.pageKey;
  let nexttotal = data.ownedNfts.length;
  for (var k = count; k < nexttotal+count ; k++){
    setImg(oldArray => [...oldArray, data.ownedNfts[k].media[0].gateway]);
    setTitle(oldArray => [...oldArray, data.ownedNfts[k].metadata.name]);
    setCont(oldArray => [...oldArray, data.ownedNfts[k].contract.address]);
    setNid(oldArray => [...oldArray, data.ownedNfts[k].metadata.edition])

  }




  } else {
    j = false;
  }
  
  }

    }

  useEffect(() => {
    getPolygonNFT(address);
  }, []);


  return (
<main className="inside p-10 shadow-xl shadow-gray-400/20">

{totalNFT === 0 ? (
<>
{totalNFT !== 0 ? (
  <h1 className="mb-10 text-4xl font-extralight" > 
<span className='text-slate-300 font-extrabold underline decoration-neutral-600'>You do not own any NFTs.</span>
</h1>
) : (
<Spinner />
)}  
</>
) : (
<>
<div className="grid space-x-3 md:grid-cols-2 lg:grid-cols-3 2xl:grid-cols-4">

{title.map ( (name, index) => {
      return (   
<div name={index} key={index}>


{nid[index] != undefined ? (  
 <a target= "_blank" rel="noreferrer" href={polygonURL + Cont[index] + "/" + nid[index]}>
) : (
 <a target= "_blank" rel="noreferrer" href={unkpolygonURL + Cont[index]}>

)}


<div className="flex flex-col items-center cursor-pointer transition-all duration-200 hover:scale-105">
<img className="h-80 w-80 rounded-2xl object-cover" src={Img[index]} alt="" 
  onError={({ currentTarget }) => {
    currentTarget.onerror = null; // prevents looping
    currentTarget.src="https://user-images.githubusercontent.com/24848110/33519396-7e56363c-d79d-11e7-969b-09782f5ccbab.png";
  }}
/>
<div className="p-5">
<h2 className="text-gray-100 text-3xl">{title[index]}</h2>
<p className="mt-2 text-sm text-gray-400">{Cont[index]}</p>
</div>
</div>
</a>
</div>
)
    })  
  }
      </div>
  </>
  )

}
</main>
  )}

Answer 1

import styles from "../styles/Home.module.css";
import React, { useEffect, useState, useRef } from "react";
import { useAddress, useMetamask, useDisconnect } from "@thirdweb-dev/react";
import Spinner from "./Spinner";

export default function NFT() {
  const address = useAddress();
  let image = "";
  let total = 0;
  const [title, setTitle] = useState([]);
  const [Img, setImg] = useState([]);
  const [Cont, setCont] = useState([]);
  const [nid, setNid] = useState([]);
  const [totalNFT, setTotalNFT] = useState(0);

  let page = "";

  const polygonURL = "https://opensea.io/assets/matic/";
  const unkpolygonURL = "https://opensea.io/assets?search[query]=";

  const getPolygonNFT = async (str) => {
    // const api = 'https://eth-mainnet.alchemyapi.io/v2/demo/getNFTs/?owner=0xfae46f94ee7b2acb497cecaff6cff17f621c693d';
    const api =
      `https://polygon-mainnet.g.alchemyapi.io/v2/demo/getNFTs/?owner=` + str;
    const response = await fetch(api);
    const data = await response.json();

    console.log(data);
    let total = data.totalCount;
    let firsttotal = data.ownedNfts.length;
    setTotalNFT(data.ownedNfts.length);
    // setPage(data.pageKey);
    let page = data.pageKey;

    for (var i = 0; i < firsttotal; i++) {
      setImg((oldArray) => [...oldArray, data.ownedNfts[i].media[0].gateway]);
      setTitle((oldArray) => [...oldArray, data.ownedNfts[i].metadata.name]);
      setCont((oldArray) => [...oldArray, data.ownedNfts[i].contract.address]);
      setNid((oldArray) => [...oldArray, data.ownedNfts[i].metadata.edition]);
    }

    let j = true;
    let count = 0;

    while (j) {
      if (page != undefined) {
        const api =
          `https://polygon-mainnet.g.alchemyapi.io/v2/demo/getNFTs/?owner=` +
          str +
          `&pageKey=` +
          page;

        const response = await fetch(api);
        const data = await response.json();
        console.log(data);

        page = data.pageKey;
        let nexttotal = data.ownedNfts.length;
        for (var k = count; k < nexttotal + count; k++) {
          setImg((oldArray) => [
            ...oldArray,
            data.ownedNfts[k].media[0].gateway,
          ]);
          setTitle((oldArray) => [
            ...oldArray,
            data.ownedNfts[k].metadata.name,
          ]);
          setCont((oldArray) => [
            ...oldArray,
            data.ownedNfts[k].contract.address,
          ]);
          setNid((oldArray) => [
            ...oldArray,
            data.ownedNfts[k].metadata.edition,
          ]);
        }
      } else {
        j = false;
      }
    }
  };

  useEffect(() => {
    getPolygonNFT(address);
  }, []);

  return (
    <main className="inside p-10 shadow-xl shadow-gray-400/20">
      {totalNFT === 0 ? (
        <>
          {totalNFT !== 0 ? (
            <h1 className="mb-10 text-4xl font-extralight">
              <span className="text-slate-300 font-extrabold underline decoration-neutral-600">
                You do not own any NFTs.
              </span>
            </h1>
          ) : (
            <Spinner />
          )}
        </>
      ) : (
        <div className="grid space-x-3 md:grid-cols-2 lg:grid-cols-3 2xl:grid-cols-4">
          {title.map((name, index) => {
            return (
              <div name={index} key={index}>
                {nid[index] != undefined ? (
                  <a
                    target="_blank"
                    rel="noreferrer"
                    href={polygonURL + Cont[index] + "/" + nid[index]}
                  >
                    <div className="flex flex-col items-center cursor-pointer transition-all duration-200 hover:scale-105">
                      <img
                        className="h-80 w-80 rounded-2xl object-cover"
                        src={Img[index]}
                        alt=""
                        onError={({ currentTarget }) => {
                          currentTarget.onerror = null; // prevents looping
                          currentTarget.src =
                            "https://user-images.githubusercontent.com/24848110/33519396-7e56363c-d79d-11e7-969b-09782f5ccbab.png";
                        }}
                      />
                      <div className="p-5">
                        <h2 className="text-gray-100 text-3xl">
                          {title[index]}
                        </h2>
                        <p className="mt-2 text-sm text-gray-400">
                          {Cont[index]}
                        </p>
                      </div>
                    </div>
                  </a>
                ) : (
                  <a
                    target="_blank"
                    rel="noreferrer"
                    href={unkpolygonURL + Cont[index]}
                  >
                    <div className="flex flex-col items-center cursor-pointer transition-all duration-200 hover:scale-105">
                      <img
                        className="h-80 w-80 rounded-2xl object-cover"
                        src={Img[index]}
                        alt=""
                        onError={({ currentTarget }) => {
                          currentTarget.onerror = null; // prevents looping
                          currentTarget.src =
                            "https://user-images.githubusercontent.com/24848110/33519396-7e56363c-d79d-11e7-969b-09782f5ccbab.png";
                        }}
                      />
                      <div className="p-5">
                        <h2 className="text-gray-100 text-3xl">
                          {title[index]}
                        </h2>
                        <p className="mt-2 text-sm text-gray-400">
                          {Cont[index]}
                        </p>
                      </div>
                    </div>
                  </a>
                )}
              </div>
            );
          })}
        </div>
      )}
    </main>
  );
}

NEXTJS 条件语句在地图内部不起作用

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