Question

我对Angular和Javascript相当新，所以需要一些指导。我想要计算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，到目前为止，这是我的代码：

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;
};

});

所以intSum函数是我遇到问题的地方 - 我想要总结所有对象的intTime属性。因此，如果object1的intTime = 1，object2的intTime = 2，object3的intTime = 3 intSum应为6。但是，我目前从IntSum获得的是123。

非常感谢任何帮助！

Answer 1

尝试：

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

而不是：

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

编辑：我建议你看看reduce函数，这是在这种情况下循环你的数组的javascript方法： https://www.w3schools.com/jsref/jsref_reduce.asp

EDIT2：您将$scope.logs.intTime初始化为""。第一个值保留在数组中并生成NaN。我建议你像这样初始化你的数组：

$scope.logs = [];

Answer 2

intTime在您的对象中定义为String。所以当你在做总和时，它实际上正在进行字符串连接。使用pasrseInt转换为Number并执行求和。

Answer 3

在求和+ =：

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;
};

Answer 4

您需要将intTime类型的string转换为int
您可以使用JavaScript reduce（）函数
- arr.reduce(callback, [initialValue])
- callback = function(accumulator, currentValue) { return accumulator + currentValue } //accumulator is the currentSum since the last callback

示例：http://jsfiddle.net/GruffBunny/4cFU3/

您的sum函数可写为：

 $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，我会将函数调用为$scope.sum($scope.logs, 'iniTime')

参考文献：
- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce?v=control
- Better way to sum a property value in an array (Using Angularjs)

在对象数组Angular

4 个答案: