Question

我有这段代码，用于从对象获取数小时并将它们乘以变量。

这是对象＆＃39; work＆＃39;

var work = [
    {'day': 27, 'hours': 7.30},
    {'day': 29, 'hours': 7.30},
    {'day': 31, 'hours': 10},
    {'day': 1, 'hours': 8.30},
    {'day': 2, 'hours': 7},
    {'day': 3, 'hours': 7},
    {'day': 5, 'hours': 7.30},
    {'day': 6, 'hours': 7},
    {'day': 7, 'hours': 7.30},
    {'day': 8, 'hours': 8},
    {'day': 9, 'hours': 9.30}
]

var payPerHour = 7;

这里是我计算工资的函数

function calculatePay()
{
    var result = 0, fResult = 0;

    for(var i = 0; i < work.length; i++) {
        Object.keys(work).forEach(function (val) {
            if (work[i].hasOwnProperty('hours'))
              result = work[i][val] * payPerHour;

            fResult += result;
        });
    }

    return fResult;
}

我用过＆＃34; hasOwnProperty＆＃34;检查财产是否＆＃34;小时＆＃34;存在于工作中。该函数的结果是NaN。为什么呢？

Answer 1

你已经通过for循环迭代了你的数组 - 然后你做了

Object.keys(work).forEach(function(val) {

这没有任何意义。 work是一个数组 - 不是对象。基本上，如果删除该行，它将起作用：

for(var i = 0; i < work.length; i++) {
  //Object.keys(work).forEach(function(val) {
    if(work[i].hasOwnProperty('hours'))
      result = work[i]["hours"] * payPerHour; //use the right property here

    fResult += result;
  //});
}

更简单的方法可能是使用Array.reduce

var totalHourPay = work.reduce(function(total, workDay) {
    if (workDay.hasOwnProperty("hours")) {
         total += workDay.hours * payPerHour;
    }

    return total;
}, 0);

Answer 2

您可以使用Javascript for..in循环，如下所示：

function calculatePay() {
    var result = 0, fResult = 0;
    for(var index in work) {
      		if(work[index].hasOwnProperty('hours'))
			result = work[index]['hours'] * payPerHour;
			fResult += result;
    }
     return fResult;
 }

Answer 3

为什么这些复杂的表达？试试这个ES6解决方案：

var work = [{'day':27,'hours':7.30},{'day':29,'hours':7.30},{'day':31,'hours':10},
           {'day':1,'hours':8.30},{'day':2,'hours':7},{'day':3,'hours':7},
           {'day':5,'hours':7.30},{'day':6,'hours':7},{'day':7,'hours':7.30},
           {'day':8,'hours':8},{'day': 9, 'hours': 9.30}],
           calculatePay=(b)=>work.reduce((c,d)=>c+d.hours*b,0)

// Test
console.log( calculatePay(7) ) // Returns 600.6 and 7 is your rate per hour

// Or redefine function calculatePay this way if you need ES5 compatibility
// function calculatePay(a) {
//   return work.reduce(function(b,c) {
//     return b + c.hours * a
//   }, 0)
// }

// And if you really needs use hasOwnProperty, define it this way
// function calculatePay(a) {
//   return work.reduce(function(b,c) {
//     return b + (c.hasOwnProperty('hours') && c.hours || 0) * a
//   }, 0)
// }

// But you dont need hasOwnProperty. You are processing simple array,
// not object. And this array is full of ordinary object literals. None of
// them does not inherits anything from another object, unless you override
// Object itself.

Answer 4

我相信这就是你想要的：

var work = [{'day': 27, 'hours': 7.30},
      {'day': 29, 'hours': 7.30},
      {'day': 31, 'hours': 10},
      {'day': 1, 'hours': 8.30},
      {'day': 2, 'hours': 7},
      {'day': 3, 'hours': 7},
      {'day': 5, 'hours': 7.30},
      {'day': 6, 'hours': 7},
      {'day': 7, 'hours': 7.30},
      {'day': 8, 'hours': 8},
      {'day': 9, 'hours': 9.30}
      ];

var payPerHour = 7;

var result = 0, fResult = 0;

function calculatePay(){

for(var i = 0; i < work.length; i++) {
   Object.keys(work).forEach(function() {

   result = work[i].hours * payPerHour;
   fResult += result;
 });

}

console.log("Final total: " +fResult);
}

calculatePay();

javascript-如何检查对象是否为特定属性

4 个答案: