如何在Angular JS的对象数组内求和货币值

Question

I have a return array of objects from a API call . And the object structure looks something like this ..

Like this the array can contain n number of Objects.

What I have to do is .. sum up all the values of all the object's selectedMapping.cost and display the sum.

But one problem is that the costs can be a bit tricky.

They can be in format like .30 or 978. etc etc for which we have to assume 0.30 and 978.00 respectively. They can be null or undefined also in which case we have to default it to 0.0

How can I achieve the sum in Angular JS ? How to handle the appropriate conversions and display the sum ?

Answer 1

This seems like a good time to use reduce

 const data = [ { selectedMapping: { cost: ".30" } }, { selectedMapping: { cost: "200" } }, { selectedMapping: { cost: ".60" } }, { selectedMapping: { cost: ".22" } }, { selectedMapping: { cost: null } }]; const sumCost = (data) => data.reduce( (cost, entry) => cost + (parseFloat(entry.selectedMapping.cost) || 0), 0 ) console.log(sumCost(data)) 

Answer 2

Hope I got you right, then this plunker I have created should do what you want: https://embed.plnkr.co/zzQkybjND5xi2Uo7dNHZ/

Simply iterate over the array, check the value for null or undefined if so set it to 0.0 and sum all values.

Answer 3

Here's my solution which handles undefined/null items

const sum = items.reduce((prevVal,item)=>{
  const selectedMapping = item.selectedMapping || null
  const cost = (isNaN(selectedMapping) && 'cost' in selectedMapping)? Number(selectedMapping.cost) : 0 
  return prevVal + cost
},0)
console.log(sum.toFixed(2))

Here's a JSBin for it

And reference for JavaScript's Map, Reduce, and Filter

Answer 4

you could map over the array and get the cost and then use R.sum method of ramdajs

const array = [
  {
    selectedMapping: {
      cost: ".30"
    }
  },
  {
    selectedMapping: {
      cost: "200"
    }
  },
  {
    selectedMapping: {
      cost: ".60"
    }
  },
  {
    selectedMapping: {
      cost: ".10"
    }
  },];

const currency = array.map(curr=>parseFloat(curr.selectedMapping.cost))
R.sum(currency); 

here is the code repel to do that.