Question

我有一个对象数组。所有这些对象不一定具有相同的属性。

如果数组中的某些对象确实具有公共属性，我需要找到它们的总和。

[{"taxAmount":572.26,"totalAmount":2004,"totalDiscount":0,"totalItems":12,"gTotal":2576.2599999999998,"count":4,"deployment":{"_id":"554c92f979d26026307a5a9b","name":"Punjabi Bagh"}},
{"taxAmount":304.9,"totalAmount":1111,"totalDiscount":0,"totalItems":9,"gTotal":1415.8999999999999,"count":2,"deployment{"_id":"554c930579d26026307a5a9c","name":"Pitampura"}},
{"deployment":{"_id":"554c930c79d26026307a5a9d","name":"Model Town"}},   
{"deployment":{"_id":"554c945079d26026307a5cae","name":"Dwarka"}},
{"deployment":{"_id":"554cd66c0a40ccd2416e38e7","name":"Green Park"}}]

在上面的例子中，我需要添加计算TaxAmount和totalAmount的个别总和。

另外，我需要一些让我们说totalAmount属性的对象。

我如何在javascript中进行此操作？

另外，有没有一种快速的方法来检查一个对象是否有任何额外的属性，除了我们到目前为止迭代的内容？

Answer 1

你走在正确的道路上 - 减少是一种方法（你还需要Object.keys来遍历每个对象的属性

注释内联 - 请注意，在计算/添加

之前，这会执行（简单）isNumber检查

var data = [{"taxAmount":572.26,"totalAmount":2004,"totalDiscount":0,"totalItems":12,"gTotal":2576.2599999999998,"count":4,"deployment":{"_id":"554c92f979d26026307a5a9b","name":"Punjabi Bagh"}},
{"taxAmount":304.9,"totalAmount":1111,"totalDiscount":0,"totalItems":9,"gTotal":1415.8999999999999,"count":2,"deployment":{_id:"554c930579d26026307a5a9c","name":"Pitampura"}},
{"deployment":{"_id":"554c930c79d26026307a5a9d","name":"Model Town"}},   
{"deployment":{"_id":"554c945079d26026307a5cae","name":"Dwarka"}},
{ "deployment": { "_id": "554cd66c0a40ccd2416e38e7", "name": "Green Park" } }]

var result = data.reduce(function (a, b) {
    // loop through the properties
    Object.keys(b).forEach(function (key) {
        // check if it's a number
        if (!isNaN(parseFloat(b[key]))) {
            // get the running count / sum for this key or initialize a new one
            a[key] = a[key] || { sum: 0, count: 0 }
            a[key].sum += Number(b[key]);
            a[key].count++;
        }
    })

    return a;
}, {})

console.log(result)

Answer 2

batchSize

此var obj = [{"taxAmount":572.26,"totalAmount":2004,"totalDiscount":0,"totalItems":12,"gTotal":2576.2599999999998,"count":4,"deployment":{"_id":"554c92f979d26026307a5a9b","name":"Punjabi Bagh"}}, {"taxAmount":304.9,"totalAmount":1111,"totalDiscount":0,"totalItems":9,"gTotal":1415.8999999999999,"count":2,"deployment":{"_id":"554c930579d26026307a5a9c","name":"Pitampura"}}, {"deployment":{"_id":"554c930c79d26026307a5a9d","name":"Model Town"}}, {"deployment":{"_id":"554c945079d26026307a5cae","name":"Dwarka"}}, {"deployment":{"_id":"554cd66c0a40ccd2416e38e7","name":"Green Park"}}], sumObj = { "taxAmount":0, "totalAmount":0 }; for( var o in obj ){ sumObj.taxAmount += obj[ o ].taxAmount || 0; sumObj.totalAmount += obj[ o ].totalAmount || 0; }测试obj[ o ].taxAmount || 0是否具有属性obj[ o ]，以及它是否真实。如果是，则返回，否则返回0.

Answer 3

假设您的数据包含在名为values的数组中：

var taxAmount = 0,
    totalAmount = 0,
    objectsWithTotalAmount = 0;
for (int i = 0; i < values.length; i++) {
    if (values[i].hasOwnProperty("taxAmount") {
        taxAmount += values[i].taxAmount;
    }
    if (values[i].hasOwnProperty("totalAmount") {
        totalAmount += values[i].totalAmount;
        objectsWithTotalAmount++;
    }
}

使用.hasOwnProperty()检查对象是否包含该属性。这样，您就可以获得taxAmount和totalAmount的总和，以及具有totalAmount属性的对象数。

Answer 4

将prop名称传递给function，检查每个数组实例的每个属性

＆＃13;

    var testArr = [{"taxAmount":572.26,"totalAmount":2004,"totalDiscount":0,"totalItems":12,"gTotal":2576.2599999999998,"count":4,"deployment":{"_id":"554c92f979d26026307a5a9b","name":"Punjabi Bagh"}},
    {"taxAmount":304.9,"totalAmount":1111,"totalDiscount":0,"totalItems":9,"gTotal":1415.8999999999999,"count":2,"deployment":{"_id":"554c930579d26026307a5a9c","name":"Pitampura"}},
    {"deployment":{"_id":"554c930c79d26026307a5a9d","name":"Model Town"}},   
    {"deployment":{"_id":"554c945079d26026307a5cae","name":"Dwarka"}},
    {"deployment":{"_id":"554cd66c0a40ccd2416e38e7","name":"Green Park"}}];
    
    var testTotal = getTotal('taxAmount');
    alert(testTotal);
    
    function getTotal(propName) {
      var total = 0;
      for (var i = 0; i < testArr.length; i++) {
        for (var key in testArr[i]) {
          if (testArr[i].hasOwnProperty(key)) {
            if (key === propName) {
              total = total + testArr[i][key];
            }
          }
        }
      }
      return total;
    }

＆＃13;

Answer 5

不确定你真正想要的是什么。是这个吗？

var obj = [{"taxAmount":572.26,"totalAmount":2004,"totalDiscount":0,"totalItems":12,"gTotal":2576.2599999999998,"count":4,"deployment":{"_id":"554c92f979d26026307a5a9b","name":"Punjabi Bagh"}},
{"taxAmount":304.9,"totalAmount":1111,"totalDiscount":0,"totalItems":9,"gTotal":1415.8999999999999,"count":2,"deployment":{"_id":"554c930579d26026307a5a9c","name":"Pitampura"}},
{"deployment":{"_id":"554c930c79d26026307a5a9d","name":"Model Town"}},   
{"deployment":{"_id":"554c945079d26026307a5cae","name":"Dwarka"}},
{"deployment":{"_id":"554cd66c0a40ccd2416e38e7","name":"Green Park"}}],
    sumObj = { "taxAmount":[], "totalAmount":[] };

for( var o in obj ){
    var current = obj[ o ];
    current.taxAmount && sumObj.taxAmount.push( current.taxAmount );
    current.totalAmount && sumObj.totalAmount.push( current.totalAmount  );
}

Answer 6

我使用递归函数，它们在Javascript中非常容易使用，只是不断传递相同的变量：

function getSumAllProps(){
   var objSums = {};
   var arrObjs = [{"taxAmount":572.26,"totalAmount":2004,"totalDiscount":0,"totalItems":12,"gTotal":2576.2599999999998,"count":4,"deployment":{"_id":"554c92f979d26026307a5a9b","name":"Punjabi Bagh"}},{"taxAmount":304.9,"totalAmount":1111,"totalDiscount":0,"totalItems":9,"gTotal":1415.8999999999999,"count":2,"deployment":{"_id":"554c930579d26026307a5a9c","name":"Pitampura"}},{"deployment":{"_id":"554c930c79d26026307a5a9d","name":"Model Town"}},{"deployment":{"_id":"554c945079d26026307a5cae","name":"Dwarka"}},{"deployment":{"_id":"554cd66c0a40ccd2416e38e7","name":"Green Park"}}];

   for( var prop in arrObjs ){
      sumProps( arrObjs[i], objSums );
   }

   console.log( objSums );
}

function sumProps( objIn, newObjSum ){
   for( var theProp in objIn ){
      if( typeof objIn[ theProp ] === 'object'){
         sumProps( objIn[ theProp ], newObjSum );
      }else{
         if( !newObjSum[ theProp ] ) newObjSum[ theProp ] = 0;
         newObjSum[ theProp ] += objIn[ theProp ];
      }
   }
}

Answer 7

您应该使用Array.prototype.reduce()方法。此外，您可以使用功能方式和高阶功能来实现。

此外，您可以使用Arguments对象来传递多个参数。

我已经制作了通用功能，以减少您的数据。

  var data = [{"taxAmount":572.26,"totalAmount":2004,"totalDiscount":0,"totalItems":12,"gTotal":2576.2599999999998,"count":4,"deployment":{"_id":"554c92f979d26026307a5a9b","name":"Punjabi Bagh"}},
{"taxAmount":304.9,"totalAmount":1111,"totalDiscount":0,"totalItems":9,"gTotal":1415.8999999999999,"count":2,"deployment":{"_id":"554c930579d26026307a5a9c","name":"Pitampura"}},
{"deployment":{"_id":"554c930c79d26026307a5a9d","name":"Model Town"}},
{"deployment":{"_id":"554c945079d26026307a5cae","name":"Dwarka"}},
{"deployment":{"_id":"554cd66c0a40ccd2416e38e7","name":"Green Park"}}];



function reducer(data, func){
  //Retrieve our arguments parameter
  var args = [].slice.call(arguments);
  //Remove first and second element from array args
  args.splice(0,2);
  //Start reducing our data, initialize with an empty object
  return data.reduce(function(result, current){
    //ForEach key
    args.forEach(function(key){
      //If our object get current key, add curent value, instead of initialize it with 0
      //Apply our high order function
      func(result, current, key);
    });
    //Return our current object result
    return result;
  }, {});
}

//Function to sum some properties
function sum(result, current, key){
  return result[key] = (result[key] || 0) + (current[key] || 0);
}

//Function to count occurence of properties
function number(result, current, key){
  return current.hasOwnProperty(key)
  ? (result[key] = (++result[key] || 1), result)
  : result
}

var res1 = reducer(data, sum, 'taxAmount', 'totalAmount');

var res2 = reducer(data, number, 'taxAmount');

因此，只需指定高阶函数，您就可以使用一个函数对特定字段求和或计算出现次数。

迭代对象数组以获得存在的数量总和

7 个答案: