Javascript 对象数组中的求和属性

我对Angular和Javascript相当陌生，因此需要一些指导。我想计算出一个对象数组中值的总和和平均值。通过输入框将对象推入数组，以下是我目前的代码：

var myApp = angular.module("myApp", []);

myApp.controller("myController", function($scope){

$scope.newLog = {};

$scope.logs = [
    {project: "", 
     phase: "", 
     date: "", 
     startTime: "", 
     intTime: "", 
     endTime: "", 
     comments: ""}
];

$scope.saveLog = function(){

    //CREATING DELTA TIME
    var newTimeLog = $scope.newLog;
    var begin = (newTimeLog.startTime).getTime();
    var end = (newTimeLog.endTime).getTime();

    var i = newTimeLog.intTime;
    var ii = parseInt(i);
    var intMilisec = ii*60000;

    if( isNaN(begin) )
        {
            return "";
        }

        if (begin < end) {
            var milisecDiff = end - begin;
        }else{
            var milisecDiff = begin - end;
        }

        var minusInt = milisecDiff - intMilisec;

        var milisec = parseInt((minusInt%1000)/100)
            , seconds = parseInt((minusInt/1000)%60)
            , minutes = parseInt((minusInt/(1000*60))%60)
            , hours = parseInt((minusInt/(1000*60*60))%24);

        hours = (hours < 10) ? "0" + hours : hours;
        minutes = (minutes < 10) ? "0" + minutes : minutes;
        seconds = (seconds < 10) ? "0" + seconds : seconds;

        var deltaFormat = hours + " Hours " + minutes + " Minutes";

    newTimeLog["deltaTime"] = deltaFormat;

    $scope.logs.push($scope.newLog);
    $scope.newLog = {};
};

$scope.intSum = function(){
    var sum = 0;
    for (var i = 0; i < $scope.logs.length; i++){
        sum += $scope.logs[i].intTime;
    }
    return sum;
};

});

 $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
     return items.reduce( function(a, b){
         return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
     }, 0);  //initially sum=0, so initialValue is 0
  };

var myApp=angular.module（“myApp”，[]）；
控制器（“myController”，函数（$scope）{
$scope.newLog={}；
$scope.logs=[
{项目：“”，
阶段：“，
日期：“，
开始时间：“，
intTime:“”，
结束时间：“，
注释：“}”
];
$scope.saveLog=函数（）{
//创建增量时间
var newTimeLog=$scope.newLog；
var begin=（newTimeLog.startTime.getTime（）；
var end=（newTimeLog.endTime）.getTime（）；
var i=newTimeLog.intTime；
var ii=parseInt（i）；
var Intmiliesec=ii*60000；
如果（isNaN（开始））
{
返回“”；
}
如果（开始<结束）{
var milisecDiff=结束-开始；
}否则{
var milisecDiff=开始-结束；
}
var minusInt=milisecDiff-intMilisec；
var milisec=parseInt（（小数%1000）/100）
，秒=parseInt（（minusInt/1000）%60）
，分钟=parseInt（（minus int/（1000*60））%60）
，hours=parseInt（（minusInt/（1000*60*60））%24）；
小时数=（小时数<10）？“0”+小时数：小时数；
分钟=（分钟<10）？“0”+分钟：分钟；
秒=（秒<10）？“0”+秒：秒；
var deltaFormat=小时数+小时数+分钟数+分钟数；
newTimeLog[“deltaTime”]=deltaFormat；
$scope.logs.push（$scope.newLog）；
$scope.newLog={}；
};
$scope.intSum=函数（）{
var总和=0；
对于（变量i=0；i<$scope.logs.length；i++）{
sum+=$scope.logs[i].intTime；
}
回报金额；
};
});

因此，

intSum

函数是我遇到问题的地方-我想对所有对象的

intTime

属性求和。因此，如果object1的

intTime=1

，object2的

intTime=2

，object3的

intTime=3

则

intSum

应该是

6

。然而，我目前从

IntSum

中得到的是

123

 $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
     return items.reduce( function(a, b){
         return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
     }, 0);  //initially sum=0, so initialValue is 0
  };

任何帮助都将不胜感激

试试看：

sum += parseInt($scope.logs[i].intTime);

 $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
     return items.reduce( function(a, b){
         return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
     }, 0);  //initially sum=0, so initialValue is 0
  };

而不是：

sum += $scope.logs[i].intTime;

 $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
     return items.reduce( function(a, b){
         return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
     }, 0);  //initially sum=0, so initialValue is 0
  };

---

编辑：我建议您看看reduce函数，在本例中，它是在数组上循环的javascript方式：

 $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
     return items.reduce( function(a, b){
         return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
     }, 0);  //initially sum=0, so initialValue is 0
  };

---

EDIT2:您将

$scope.logs.intTime

初始化为

“

”。第一个值保留在数组中并生成

NaN

。 我建议您按如下方式初始化阵列：

$scope.logs = [];

 $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
     return items.reduce( function(a, b){
         return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
     }, 0);  //initially sum=0, so initialValue is 0
  };

---

intTime在对象中定义为字符串。因此，当您进行求和时，它实际上是在进行字符串串联。使用pasrseInt转换为数字并求和。

当求和+=”时，尝试使用parseInt：

$scope.intSum = function(){
    var sum = 0;
    for (var i = 0; i < $scope.logs.length; i++){
        sum += parseInt($scope.logs[i].intTime);
    }
    return sum;
};

 $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
     return items.reduce( function(a, b){
         return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
     }, 0);  //initially sum=0, so initialValue is 0
  };

$scope.intSum=function（）{
var总和=0；
对于（变量i=0；i<$scope.logs.length；i++）{
sum+=parseInt（$scope.logs[i].intTime）；
}
回报金额；
};

您需要将

string

类型的

intTime

转换为

int

可以使用JavaScript reduce（）函数

 $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
     return items.reduce( function(a, b){
         return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
     }, 0);  //initially sum=0, so initialValue is 0
  };

• arr.reduce（回调，[initialValue]）

• callback=function（accumulator，currentValue）{return accumulator+currentValue}//accumulator是自上次回调以来的当前和

例如：

 $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
     return items.reduce( function(a, b){
         return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
     }, 0);  //initially sum=0, so initialValue is 0
  };

• 求和函数可以写成：

   $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
       return items.reduce( function(a, b){
           return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
       }, 0);  //initially sum=0, so initialValue is 0
    };
  

• 在您的情况下，我将以

  $scope.sum（$scope.logs，'iniTime'）的形式进行函数调用。

参考资料：

 $scope.sum = function(items, prop){ //items is the array, prop is the property you want to its value to be calculated 
     return items.reduce( function(a, b){
         return a + parseInt(b[prop]);  //in the first attempt, a=0 which is the same as initialValue
     }, 0);  //initially sum=0, so initialValue is 0
  };

---

这很有帮助，谢谢。但是它仍然会被卡住，出于某种原因，每次我单击save按钮切换saveLog（）时，它都会将intSum（）中的sum变量设置为NaN？为了帮助您更多，我需要您修改后的js文件和html来重现您的问题。