Question

我正在尝试在JS中创建对象的对象，但我认为我在异步执行方面存在一些问题。

这是我的代码：

// Extract data (episode number, characters firstname's) from .docx to JSON

var mammoth = require("mammoth")

function docx2Object (filepath) {
    
    return mammoth.extractRawText({path: filepath})
    .then(function (res) {
        return res.value;
    })
    .then(function (res) {
        let arr = {}
        arr["number"] = "" + res.match(/(?!Episode #)\d+/)
        arr["names"] = [...new Set(res.match(/^[^:\r\n]+(?=:)/gm))]
        return arr
    })
}

function files2JSON (arrayScripts) {
    
    let arr = {}
    let i = 0
    arrayScripts.forEach(function(element) {
        docx2Object(element).then(function (res) {
            arr[i++] = res
            console.log(JSON.stringify(arr, null, '\t'))
        })
    })
    return JSON.stringify(arr, null, '\t')
}

let arrayScripts = ["doc1.docx", "doc2.docx"]
console.log(files2JSON(arrayScripts))

这是输出：

{}

{
    "0": {
        "number": "10600",
        "names": [
            "Hilary",
            "Jean-Claude",
            "Devon",
            "Jean Claude",
            "Cane",
            "Lily",
            "Jack",
            "Phyllis",
            "Victor",
            "Nikki",
            "Neil",
            "Paul",
            "Dr. Barrett",
            "Christine",
            "Kelly"
        ]
    }
}
{
    "0": {
        "number": "10600",
        "names": [
            "Hilary",
            "Jean-Claude",
            "Devon",
            "Jean Claude",
            "Cane",
            "Lily",
            "Jack",
            "Phyllis",
            "Victor",
            "Nikki",
            "Neil",
            "Paul",
            "Dr. Barrett",
            "Christine",
            "Kelly"
        ]
    },
    "1": {
        "number": "10601",
        "names": [
            "Hilary",
            "Devon",
            "Jean+Claude",
            "Jean + Claude",
            "Jean/Claude",
            "Jean / Claude",
            "Cane",
            "Lily",
            "Jack",
            "Phyllis",
            "Victor",
            "Nikki",
            "Neil",
            "Paul",
            "Dr. Barrett",
            "Christine",
            "Kelly"
        ]
    }
}

我的数组是空的，我的索引不匹配。任何人都可以帮忙吗？

Answer 1

我认为你的问题在于

arrayScripts.forEach(function(element) {
    docx2Object(element).then(function (res) {
        arr[i++] = res
        console.log(JSON.stringify(arr, null, '\t'))
    })
})

docx2Object调用是异步的，意味着forEach的迭代将立即返回并执行。这意味着files2JSON可能在所有处理完成之前执行。

您最想做的就是将每个promise存储到一个数组中，然后使用Promise.all()一次解决所有这些问题并从Promise.all()返回promise并等待它。总的来说，这个结构看起来像

function asyncTask1(task) {
  return getPromise(task);
}

function asyncTask2() {
  var tasks = ["eat", "sleep"];
  var promises = tasks.map(function(task) {
    return asyncTask1(task);
  });
  return Promise.all(promises);
}

asyncTask2().then(function(response) {
  console.log("I ate and slept.");
});

我个人在调试异步代码时所做的第一件事就是抛出一大堆console.log并看看什么时候执行。它确实有助于查看执行顺序。

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all

Answer 2

这将有助于获取输出。当您使用全局错误的增量计数以及包含错误代码的mammoth.extractRawText（）方法时。

// Extract data (episode number, characters firstname's) from .docx to JSON
var mammoth = require("mammoth");

function docx2Object (filepath) {

  return mammoth.extractRawText({path: filepath})
      .then(function (res) {
        return res.value;
      }).then(function (res) {
        var arr = {};
        arr["number"] = "" + res.match(/(?!Episode #)\d+/);
        //arr["names"] = [...new Set(res.match(/^[^:\r\n]+(?=:)/gm))];
        return arr
      });

}

function files2JSON (arrayScripts) {
  var arr = {};

  arrayScripts.forEach(function(element,index) {
    docx2Object(element).then(function (res) {
      arr[index++] = res;
      console.log(res,index)
      console.log(JSON.stringify(arr, null, '\t'));
    })
  });
  return JSON.stringify(arr, null, '\t');
}

var arrayScripts = ["doc1.docx", "doc2.docx"];
console.log(files2JSON(arrayScripts));

创建对象的对象

2 个答案: