Javascript过滤器空对象属性

Question

我有一个包含一个或多个对象的数组，我想过滤掉所有null属性：

asset = [{"ObjId":177791,"ObjCreditlineM":"DEU","ObjReprorechtM":null,"ObjKommentarM":null,"ObjZustandM":null,"ObjReserve01M":null,"ObjReserve02M":null,"ObjFeld01M":null,"ObjFeld02M":null,"ObjFeld03M":null,"ObjFeld04M":"Foto","ObjFeld05M":null,"ObjFeld06M":null,"ObjFeld07M":null,"ObjFeld01S":null,"ObjFeld02S":null,"ObjFeld03S":null,"ObjFeld04S":null,"ObjFeld05S":null,"ObjFeld06S":null,"ObjFeld07S":null,"ObjFeld01F":0,"ObjFeld02F":0,"ObjFeld01D":null,"ObjFeld02D":null,"ObjInv01S":null,"ObjInv02S":null,"ObjInv03S":null,"ObjInv04S":null,"ObjInv05S":null,"ObjInv06S":null,"ObjDinId":0,"ObjReferenz01Id":null,"ObjReferenz02Id":null,"ObjTransferId":null,"ObjGesperrtS":null,"ObjIconTextM":null}]


// My attempt:

var filledProps = asset.map(el => { 
  if (Object.keys(el)) { // check if object property value is not null
    return el;
  };
});

console.log(filledProps);

但是我又得到了相同的对象属性。我想念什么？

Answer 1

听起来好像您想使用仅具有非null原始属性的新对象创建新数组。是的，这map是您要开始的地方，但Object.keys(el)始终是真实的，因为它返回属性名称数组。您虽然接近：

var asset = [{"ObjId":177791,"ObjCreditlineM":"DEU","ObjReprorechtM":null,"ObjKommentarM":null,"ObjZustandM":null,"ObjReserve01M":null,"ObjReserve02M":null,"ObjFeld01M":null,"ObjFeld02M":null,"ObjFeld03M":null,"ObjFeld04M":"Foto","ObjFeld05M":null,"ObjFeld06M":null,"ObjFeld07M":null,"ObjFeld01S":null,"ObjFeld02S":null,"ObjFeld03S":null,"ObjFeld04S":null,"ObjFeld05S":null,"ObjFeld06S":null,"ObjFeld07S":null,"ObjFeld01F":0,"ObjFeld02F":0,"ObjFeld01D":null,"ObjFeld02D":null,"ObjInv01S":null,"ObjInv02S":null,"ObjInv03S":null,"ObjInv04S":null,"ObjInv05S":null,"ObjInv06S":null,"ObjDinId":0,"ObjReferenz01Id":null,"ObjReferenz02Id":null,"ObjTransferId":null,"ObjGesperrtS":null,"ObjIconTextM":null}]

// Use `map` to get a new array with new objects
var filledProps = asset.map(el => {
  // Loop the property names of `el`, creating a new object
  // with the ones whose values aren't `null`.
  // `reduce` is commonly used for doing this:
  return Object.keys(el).reduce((newObj, key) => {
    const value = el[key];
    if (value !== null) {
      newObj[key] = value;
    }
    return newObj;
  }, {});
});
console.log(filledProps);

我想念什么？

由于if (Object.keys(el))始终是真实的，因此您的代码总是始终返回el不变。它不是在创建新对象，也不是在删除属性null从原始对象中值的属性。

上面创建了新对象，但是如果您愿意，您可以从具有null值的原始文件中删除属性：

var asset = [{"ObjId":177791,"ObjCreditlineM":"DEU","ObjReprorechtM":null,"ObjKommentarM":null,"ObjZustandM":null,"ObjReserve01M":null,"ObjReserve02M":null,"ObjFeld01M":null,"ObjFeld02M":null,"ObjFeld03M":null,"ObjFeld04M":"Foto","ObjFeld05M":null,"ObjFeld06M":null,"ObjFeld07M":null,"ObjFeld01S":null,"ObjFeld02S":null,"ObjFeld03S":null,"ObjFeld04S":null,"ObjFeld05S":null,"ObjFeld06S":null,"ObjFeld07S":null,"ObjFeld01F":0,"ObjFeld02F":0,"ObjFeld01D":null,"ObjFeld02D":null,"ObjInv01S":null,"ObjInv02S":null,"ObjInv03S":null,"ObjInv04S":null,"ObjInv05S":null,"ObjInv06S":null,"ObjDinId":0,"ObjReferenz01Id":null,"ObjReferenz02Id":null,"ObjTransferId":null,"ObjGesperrtS":null,"ObjIconTextM":null}];

asset.forEach(el => {
  Object.keys(el).forEach(key => {
    if (el[key] === null) {
      delete el[key];
    }
  });
});
console.log(asset);

不过，有两个方面需要注意：

• 它修改了原始对象（因此以某种方式修改了原始数组）。
• 当您从对象中删除属性时，它可能会影响该对象之后的属性查找性能。您不在乎的时间有99.999％，但是它在那里。