use parseFloat inside of an array

Question

How can i use parseFloat when data lives inside of an array?

Let's say that i get an api response like this:

$scope.response = [{name: "Richard", qty: "350.99"},
{name: "Chuck", qty: "199"},
{name: "Phonenix", qty: "233.77"}]

I want to sum the values of qty, but i cannot 'cause the data type. If i need to use parseFloat over qty, how can i get only those values?

I have to use something like some() to get qty values?

I'm using AngularJs and Javascript.

reduce it to return a sum. $scope.response.reduce((a,b) => a + parseFloat(b.qty)); — Sterling Archer
– Sterling Archer, Commented Jan 10, 2018 at 17:48

felixmosh · Accepted Answer · 2018-01-11 05:27:39Z

3

You can iterate over the Array and calculate the sum using Array.reduce

const arr = [{
    name: "Richard",
    qty: "350.99"
  },
  {
    name: "Chuck",
    qty: "199"
  },
  {
    name: "Phonenix",
    qty: "233.77"
  }
];

const result = arr.reduce((sum, current) => {
  return sum + parseFloat(current.qty);
}, 0);

console.log(result);

edited Jan 11, 2018 at 5:27

answered Jan 10, 2018 at 17:49

felixmosh

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1 Comment

Jackson Lenhart Over a year ago

You don't need to do the reassignment sum += since reduce passes the return value to each iteration you can just add them together

Hassan Imam · Accepted Answer · 2018-01-10 17:48:43Z

2

Use array#reduce to sum all qty of response array.

var response = [{name: "Richard", qty: "350.99"},{name: "Chuck", qty: "199"},{name: "Phonenix", qty: "233.77"}],
    result = response.reduce((sum, {qty}) => sum += +qty, 0);

console.log(result);

answered Jan 10, 2018 at 17:48

Hassan Imam

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1 Comment

Jackson Lenhart Over a year ago

This is cool, I like the destructuring. But isn't the reassignment sum += qty unnecessary when you can just add them together like sum + qty?

Jackson Lenhart · Accepted Answer · 2018-01-10 17:56:02Z

2

You could use reduce for this:

const response = [
  {name: "Richard", qty: "350.99"},
  {name: "Chuck", qty: "199"},
  {name: "Phonenix", qty: "233.77"}
];

const sumQuantities =
  response.reduce((acc, x) =>
    acc + parseFloat(x.qty)
  , 0);
    
console.log(sumQuantities);

answered Jan 10, 2018 at 17:56

Jackson Lenhart

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Comments

KevBot · Accepted Answer · 2018-01-10 17:59:50Z

2

You can map the array to return the parseFloat of the qty, then use reduce to add the values.

var response = [{
    name: "Richard",
    qty: "350.99"
  },
  {
    name: "Chuck",
    qty: "199"
  },
  {
    name: "Phonenix",
    qty: "233.77"
  }];

var sum = response.map(function(obj) {
    return parseFloat(obj.qty);
  })
  .reduce(function(a, b) {
    return a + b;
  }, 0);
  
console.log(sum)

edited Jan 10, 2018 at 17:59

answered Jan 10, 2018 at 17:49

KevBot

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2 Comments

RaphaMex Over a year ago

don't forget the default value to reduce as 2nd param

KevBot Over a year ago

Great catch @RaphaMex. Thank you

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