Question

let traveler = [{
    timestamp: 'qualia',
    firstname: 'unborn',
    lastname: 'child',
    location: 'null'
    },
    {
    timestamp: 1000,
    firstname: 'Olivia',
    lastname: 'Kirshner',
    location: 'Titan'
    },
    {
    timestamp: 1001,
    firstname: 'James',
    lastname: 'Cole',
    location: 'Emerson Hotel'
}]

// function noerror(splinter = traveler[0]) {
//     return [{firstname, lastname}] = splinter
// }

function restructure(time) {
    // if no array is returned on the lookup, and the value flags as undefined in restructure()
    let missingLink = traveler[0]
    let tempArray = traveler
        .filter((item) => item.timestamp === time)
    try {
        if (tempArray.firstname !== 'undefined' || tempArray.firstname !== 'null') { // check does not work
            return [{ firstname, lastname }] = tempArray

        } 
        // else {
        //     return [{firstname, lastname}] = missingLink
        // }
    } catch (e) {
        // e instanceof TypeError // boolean error type check
        switch (e.name) {
            case 'TypeError':
                console.error(`Could not complete your request: ${e.message}`);
                // return [{firstname, lastname}] = missingLink
            default:
                break;
        }
    } 
}

restructure(1001)
console.log(`firstname: ${firstname}, lastname: ${lastname}`)

restructure(100)
console.log(`firstname: ${firstname}, lastname: ${lastname}`)

restructure(1000)
lastname = 'Redforester' // temporary assignment to the variable, by value, not to the Object
console.log(`firstname: ${firstname}, lastname: ${lastname}`)

restructure(1000)

42号线让我头疼。

当传递给过滤器的搜索键产生空白数组时，我试图从捕获的异常循环中返回默认值。

该错误由console.error（）处理，因此运行代码可查看错误是什么。

您知道一种允许从捕获的异常循环返回默认值的方法吗？

该行已被注释掉，但是尝试它会导致新的错误：

 return [{firstname, lastname}] = missingLink

Answer 1

使用filter返回一个数组。因此，tempArray是一个数组，没有firstname和lastname属性。

为此，我建议您将filter()切换为find()，并在解构过程中删除[]：

let traveler = [{
    timestamp: 'qualia',
    firstname: 'unborn',
    lastname: 'child',
    location: 'null'
    },
    {
    timestamp: 1000,
    firstname: 'Olivia',
    lastname: 'Kirshner',
    location: 'Titan'
    },
    {
    timestamp: 1001,
    firstname: 'James',
    lastname: 'Cole',
    location: 'Emerson Hotel'
}]

// function noerror(splinter = traveler[0]) {
//     return [{firstname, lastname}] = splinter
// }

function restructure(time) {
    // if no array is returned on the lookup, and the value flags as undefined in restructure()
    let missingLink = traveler[0]
    let tempArray = traveler
        .find((item) => item.timestamp === time)
    
    try {
        if (tempArray.firstname !== 'undefined' || tempArray.firstname !== 'null') { // check does not work
          return { firstname, lastname } = tempArray

        } 
        // else {
        //     return [{firstname, lastname}] = missingLink
        // }
    } catch (e) {
        // e instanceof TypeError // boolean error type check
        switch (e.name) {
            case 'TypeError':
                console.error(`Could not complete your request: ${e.message}`);
                return {firstname, lastname} = missingLink
            default:
                break;
        }
    } 
}

restructure(1001)
console.log(`firstname: ${firstname}, lastname: ${lastname}`)

restructure(100)
console.log(`firstname: ${firstname}, lastname: ${lastname}`)

restructure(1000)
lastname = 'Redforester' // temporary assignment to the variable, by value, not to the Object
console.log(`firstname: ${firstname}, lastname: ${lastname}`)

restructure(1000)

Answer 2

我相信您要搜索的关键字是throw

包含捕获到catch(error){}中的任何error的{{1}}短语。
例如：

try{}

如果您没有从try { throw "me" } catch(error){ // value of error is "me" console.log(error); }投掷任何东西，则传播将从此处停止。

因此，抛出“我们” 会将错误传播到父函数。因此：

catch

如何从捕获的异常循环中返回值？

2 个答案: