Javascript：物件陣列，檢查專案是否有值

鑒于我有以下腳本，我如何才能只計算陣列項是否定義了值，在以下場景中我得到 3，因為它計算陣列，但我如何檢查 firstName 或 lastname 的實際陣列屬性是不為空，我希望它計算是否填充了名字或姓氏。

var x = [{"firstName":"guest1fnamee","lastName":"guest1fnamee"},{"firstName":"guest2fnamee","lastName":"guest2lnamee"},{"firstName":"","lastName":""}]

var noGuests = 0
for (a in x) {
 noGuests  
}    
alert(noGuests)

更新 我的應用程式的 javascript 渲染引擎已過時，無法使用過濾器。

蜘蛛猴 1.8.5

uj5u.com熱心網友回復：

您可以按專案過濾陣列item.firstName并且item.lastName不為空并獲取length結果陣列的

var x = [{"firstName":"guest1fnamee","lastName":"guest1fnamee"},{"firstName":"guest2fnamee","lastName":"guest2lnamee"},{"firstName":"","lastName":""}]

const result = x.filter(item => item.firstName && item.lastName).length;

console.log(result);

uj5u.com熱心網友回復：

如果填充了 firstName 或 lastName 中的任何一個，那么這將計算在內。如果您需要 firstName 和 lastName ，則將條件從 更改||為&&。

var x = [{"firstName":"guest1fnamee","lastName":"guest1fnamee"},{"firstName":"guest2fnamee","lastName":"guest2lnamee"},{"firstName":"","lastName":""}]

var noGuests = 0
for (a in x) {
 if (x[a]['firstName'] || x[a]['lastName']) {
    noGuests  
 }
}

console.log(noGuests);

或者可以使用 forEach 回圈這樣做

var x = [{"firstName":"guest1fnamee","lastName":"guest1fnamee"},{"firstName":"guest2fnamee","lastName":"guest2lnamee"},{"firstName":"","lastName":""}]

var noGuests = 0
x.forEach(x => {
  if (x.firstName || x.lastName) noGuests  ;
})

console.log(noGuests);

uj5u.com熱心網友回復：

function count_non_empty(collection) {
  return filter_non_empty(collection).length;
}

function filter_non_empty(collection) {
  return collection
    && collection.length
    && collection.filter(elem =>
      (elem.firstName || '').trim() // <--- If firstName is empty or empty-like string
      || (elem.lastName || '').trim()  // <--- If lastName is empty or empty-like string
    ) || [];
}

插圖

function count_non_empty(collection) {
  return filter_non_empty(collection).length;
}

function filter_non_empty(collection) {
  return collection &&
    collection.length &&
    collection.filter(elem =>
      (elem.firstName || '').trim() // <--- If firstName is empty or empty-like string
      ||
      (elem.lastName || '').trim() // <--- If lastName is empty or empty-like string
    ) || [];
}

let onlyLastName = {
  "firstName": "",
  "lastName": "SomeLastName"
};
let onlyFirstName = {
  "firstName": "SomeFirstName",
  "lastName": ""
};
let emptyLookingFirstName = {
  "firstName": "   ",
  "lastName": "SomeLastName"
};
let emptyLookingLastName = {
  "firstName": "  SomeFIrstName ",
  "lastName": "   "
};
let havingBoth = {
  "firstName": "guest1fnamee",
  "lastName": "guest1fnamee"
};
let notHavingAny = {
  "firstName": "   ",
  "lastName": ""
}

let x = [{
    "firstName": "guest1fnamee",
    "lastName": "guest1fnamee"
  },
  {
    "firstName": "guest2fnamee",
    "lastName": "guest2lnamee"
  },
  {
    "firstName": "   ",
    "lastName": ""
  }
];

console.log("Count - x:", count_non_empty(x));
console.log("Count:", count_non_empty([onlyLastName, onlyFirstName, havingBoth]));
console.log("Count:", count_non_empty([onlyLastName, onlyFirstName, havingBoth, emptyLookingFirstName]));
console.log("Count:", count_non_empty([onlyLastName, onlyFirstName, havingBoth, emptyLookingLastName]));
console.log("Count - Not Having Any:", count_non_empty([notHavingAny]));
console.log("Count - Having Both:", count_non_empty([havingBoth]));
console.log("Count - Not Having Any with Having Both:", count_non_empty([notHavingAny, havingBoth]));
console.log("Count - Not Having Any with Empty Looking First Name:", count_non_empty([notHavingAny, emptyLookingFirstName]));
console.log("Count - Not Having Any with Empty Looking Last Name:", count_non_empty([notHavingAny, emptyLookingLastName]));

WYSIWYG=>WHAT YOU SHOW IS WHAT YOU GET

標籤：javascript 数组

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