ReactJS：无法通过异步函数外部的二维数组进行解析

Question

尝试在异步函数中设置数组的状态，并在异步函数中访问它工作正常。但是当我尝试在异步函数之外访问它时，它只通过第一层解析意味着 bookDetails[0]，而解析 bookDetails[0][0] 给出了一个错误 "cannot-read-property-0-of-undefined"

getAll = async () => {
    const { contract } = this.state;
    const response = await contract.methods.getBooks().call();
    this.setState({ bookDetails: response});
    console.log("books: ",this.state.bookDetails[0][0]);

  };


//OUTPUT=> books:  nanme

//console.log outside the async function gives error

Answer 1

请注意 setState 本身并不同步，您必须在其回调中检查更新后的状态：

getAll = async () => {
    const { contract } = this.state;
    const response = await contract.methods.getBooks().call();
    this.setState({ bookDetails: response}, () => console.log("books: ",this.state.bookDetails[0][0]);
);};

除此之外，该代码段不足以验证您无法正确登录的外部异步功能的原因。请提供更完整的代码段。

ReactJS：无法通过异步函数外部的二维数组进行解析

ReactJS: Unable to parse through a 2d array outside async function

arrays

mapping

reactjs

solidity