How to change each value from an array inside an array of objects?

Question

Basically I have an array of objects. Each object has an array which I need to change the values.

I'm using React, so this is a state:

[
  {
    "points": [
      60,
      5,
      60,
      20,
      70,
      20,
      70,
      15
    ],
    "finished": true,
    "color": "#6292C6"
  },
  {
    "points": [
      80,
      15,
      80,
      25,
      90,
      25
    ],
    "finished": true,
    "color": "#3FD971"
  },
  {
    "cultureName": "",
    "points": [],
    "finished": false
  }
]

What's the best way to change the points values of this state? I need to multiply them by a factor (4.96).

Dupocas · Accepted Answer · 2019-10-30 13:53:40Z

12

map your array, spread each object inside it overwriting only the property points (map multiplying each item by the factor 4.96)

const data = [{id: 1, points: [1,2,3]}, {id: 2, points: []}]

const changedData = data.map(item =>({
    ...item,
    points : item.points.map(value => value * 4.96)
}))

console.log(changedData)

edited Oct 30, 2019 at 13:53

answered Oct 25, 2019 at 17:08

Dupocas

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Comments

Willman.Codes · Accepted Answer · 2019-10-25 17:21:38Z

2

Use nested maps

const myData = [
    {"points": [60,5,60,20,70,20,70,15],"finished": true,"color": "#6292C6"},
    {"points": [80,15,80,25,90,25],"finished": true,"color": "#3FD971"},
    {"cultureName": "","points": [],"finished": false}
]
  
  
  const newArray = myData.map(elm=>{
    const points = elm.points.map(point=> point*4.96)
    return {...elm , points}
  })
  
  console.log(newArray)

edited Oct 25, 2019 at 17:21

answered Oct 25, 2019 at 17:15

Willman.Codes

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Comments

michimo · Accepted Answer · 2019-10-25 17:12:24Z

1

const factor = 4.96
const arrayOfObject = [] // .. here your array of objects
const modifiedArrayOfObjects = arrayOfObject.map( stats => {
  const newPoints = stats.points.map(point => point * factor)
  stats.points = newPoints
  return stats
}

Here I make a new array of objects, where I map each object to one, where each point has been multiplied by your factor.

answered Oct 25, 2019 at 17:12

michimo

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