Angular 8：从数组中删除空对象

Question

我正在使用Angular8，想要从数组中删除空对象，并获取其长度。

Array: [
{data01: "abc", data02: "cde", data03: "fgh", data04: "", data05: ""},
{data01: "abc", data02: "cde", data03: "", data04: "", data05: ""},
{data01: "abc", data02: "cde", data03: "fgh", data04: "ijk", data05: "lmn"},
{data01: "abc", data02: "", data03: "", data04: "", data05: ""},
]

然后我希望它变成这样

Array: [
{data01: "abc", data02: "cde", data03: "fgh"},
{data01: "abc", data02: "cde"},
{data01: "abc", data02: "cde", data03: "fgh", data04: "ijk", data05: "lmn"},
{data01: "abc"},
]

有没有什么方法可以实现？

我尝试将这些元素推到一个新数组中，如下所示：

_Array: ["abc","cde", "fgh", "", "", ....] 

尝试将其分为5个块, 然后使用filter(Boolean)进行过滤，虽然有效，但性能有点慢，是否有其他方法可以改善性能？

- Lynn

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这个怎么样？https://dev59.com/JnVC5IYBdhLWcg3wdw65#286162 - Sameer

你能否在问题中包含你现有的代码？ - Rohit Mishra

arr.map(i => Object.entries(i).filter(([k,v]) => v).reduce((acc,[k,v]) => ({...acc, [k]: v}), {})) - Amir Popovich

你的代码很好，但我想要获取长度，但是你的代码似乎无法实现。 - Lynn

Answer 1

你可以使用JS中的Array对象方法map()和filter()来解决问题。

let array = [
{data01: "abc", data02: "cde", data03: "fgh", data04: "", data05: ""},
{data01: "abc", data02: "cde", data03: "", data04: "", data05: ""},
{data01: "abc", data02: "cde", data03: "fgh", data04: "ijk", data05: "lmn"},
{data01: "abc", data02: "", data03: "", data04: "", data05: ""},
]; // array provided

array = array.map(object => {
          let entries = Object.entries(object); //for each element in the array get the entries, [key, value] pair
          entries = entries.filter(([key, value]) => value !== ""); // remove the elements which has "" values
          return Object.fromEntries(entries);
          });
console.log(array.length);
// shorter version
array = array.map(object => Object.fromEntries(Object.entries(object).filter(([key, value]) => value !== "")));
console.log(array.length);

如果输入数组中有一个对象，该对象的所有条目都是""（空字符串），则有可能导致结果数组包含一个空对象。例如：{data01: "", data02: "", data03: "", data04: "", data05: ""}。在这种情况下，我们需要使用另一个filter()来从结果数组中删除空对象。

let array = [
    {data01: "abc", data02: "cde", data03: "fgh", data04: "", data05: ""},
    {data01: "abc", data02: "cde", data03: "", data04: "", data05: ""},
    {data01: "abc", data02: "cde", data03: "fgh", data04: "ijk", data05: "lmn"},
    {data01: "abc", data02: "", data03: "", data04: "", data05: ""},
    ]; // array provided

    array = array.map(object => {
              let entries = Object.entries(object);
              entries = entries.filter(([key, value]) => value !== "");
              return Object.fromEntries(entries);
              });
    // remove the empty object if present
    array = array.filter(object => Object.entries(object).length !== 0);
    console.log(array.length);
    // shorter version
    array = array.map(object => Object.fromEntries(Object.entries(object).filter(([key, value]) => value !== ""))).filter(object => Object.entries(object).length !== 0);
    // the filter() at the  end removes the empty object
    console.log(array.length);

- hrithik gautham TG

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这正是我所期望的！但如果能将新数组推入[key]: value中会更好。 - Lynn

Answer 2

您可以使用纯JavaScript实现此操作。请尝试以下代码。

var arr = [
{data01: "abc", data02: "cde", data03: "fgh", data04: "", data05: ""},
{data01: "abc", data02: "cde", data03: "", data04: "", data05: ""},
{data01: "abc", data02: "cde", data03: "fgh", data04: "ijk", data05: "lmn"},
{data01: "abc", data02: "", data03: "", data04: "", data05: ""},
]

arr.forEach(function(element){
for (var key in element) {
    if (element[key] === "") {
        delete element[key]
    }
}
});

console.log(arr)

- Jacob Nelson

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这段代码很好，但我试图获取长度，但似乎无法实现。 - Lynn