循环遍历对象数组，并按对象元素ID返回每个总计值的总和 [英] Loop through array of objects and return sum of each total values by object element id

问题描述

我计算税款是一种非常复杂的开票方式.我无法解释整个过程，但是如果您有任何疑问，我会尽力回答.

I'm calculating taxes for a very complicate invoicing approach. I can't explain the whole process but if you have questions I will answer as best as I can.

我想出了JS中的对象数组:

I come up with an array of objects in JS:

[
 {row_id: "20003859", expense_id: "429", tax_select: "tax1", tax_id: "1", tax_name: "GST 5%", tax_no: "", tax_value: "13.23"}, 
 {row_id: "20003859", expense_id: "429", tax_select: "tax2", tax_id: "3", tax_name: "QST 9.975%", tax_no: "", tax_value: "26.38"}, 
 {row_id: "20003840", expense_id: "409", tax_select: "tax1", tax_id: "1", tax_name: "GST 5%", tax_no: "", tax_value: "13.23"}, 
 {row_id: "20003840", expense_id: "409", tax_select: "tax2", tax_id: "3", tax_name: "QST 9.975%", tax_no: "", tax_value: "26.38"},
 {row_id: "20003870", expense_id: "419", tax_select: "tax1", tax_id: "2", tax_name: "HST 13%", tax_no: "", tax_value: "34.39"}
]

如您所见，我有3个tax_id:1、2和3.我可以有很多，但为简单起见，我只设置了3个.

As you can see I have 3 tax_ids: 1, 2 and 3. I can have many but for the sake of simplicity I put only 3.

我需要 遍历此对象数组并提出另一个对象数组 ，其总数按tax_id:

I need to loop through this array of objects and come up with another array of objects having the totals by tax_id:

[
 {tax_name: "GST 5%", total_tax: sum of tax_value for tax_id = 1},
 {tax_name: "QST 9.975%", total_tax: sum of tax_value for tax_id = 3},
 {tax_name: "HST 13%", sum of tax_value for tax_id = 2}
]

此后，我可以遍历此数组并显示每个税项的总计，加上小计并显示总发票.

After that I can loop through this array and display the totals of each tax, adding subtotal and display the total invoice.

此外，我应该按tax_select对其进行排序，但这是我可以接受的事情.

Also, I should sort them by tax_select but this it's a thing I can live with.

我尝试过:其中selected_taxes是对象的第一个数组

I have tried to: where selected_taxes is the first array of objects

 for (i = 0; i < selected_taxes.length; i++){
        var sum = 0;
    $.each( selected_taxes[i], function( tax_id, tax_value ) {
        sum += tax_value;
    });
    console.log(sum);
 }

但没有运气.

非常感谢您的帮助或建议.

Many thanks for your help or suggestions.

推荐答案

我认为Array.prototype.reduce将是您最好的选择:

I think Array.prototype.reduce will be your best bet for this:

var totals = data.reduce(function(c,x){
    if(!c[x.tax_id]) c[x.tax_id] = {
        tax_name: x.tax_name,
        tax_id: x.tax_id, 
        total_tax: 0
    };
    c[x.tax_id].total_tax += Number(x.tax_value);
    return c;
}, {});

此方法生成的对象具有其税号ID作为其属性.如果您真的想要一个平面数组，可以在事实之后将其转换为数组:

This approach generates an object that has, as its properties, the tax ID numbers. If you really want a flat array from that, you can convert that into an array after the fact:

var totalsArray = [];
for(var taxId in totals){
    totalsArray.push(totals[taxId]):
}

演示: http://jsfiddle.net/3jaJC/1/

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