Add an array to array of objects in javascript

Question

I have two variables which is an array and array of object, I want to add the value of first variable(distance) to second variable(list)

The following works fine, but I want to know if there's any other method to get some result.

let distance = [100,200,300]
let list = [ {"city" : "paris"} , {"city" : "london"} , { "city" : "barcelona" }]
for(let i = 0; i < distance.length;i++){
  let listDistance = list.map(el => {
      return Object.assign({}, el, {distance:distance[i++]})
      return el
  });

console.log(listDistance) 
}


// output [ {city : paris , distance : 100 } , {city : london  , distance : 200 } , { city : barcelona , distance : 300 }]

You don't need for loop. Just use the second parameter index from map's callback — adiga
– adiga, Commented Dec 13, 2019 at 9:28
I'm voting to close this question as off-topic because it's "How can I improve my code" kind of question therefore, it's more suitable here: codereview.stackexchange.com. — Sebastian Kaczmarek
– Sebastian Kaczmarek, Commented Dec 13, 2019 at 9:32
I made you a snippet. Your code does not work. You have a for loop AND a map and you console.log an unknown object. Anyway you have several answers now :) — mplungjan
– mplungjan, Commented Dec 13, 2019 at 9:57

mplungjan · Accepted Answer · 2019-12-13 09:53:30Z

3

Like this?

let distance = [100,200,300]
let list = [ {"city" : "paris"} , {"city" : "london"} , { "city" : "barcelona" }]

list.forEach((city,i) => city.distance = distance[i])

console.log(list)

Older browsers

let distance = [100,200,300]
let list = [ {"city" : "paris"} , {"city" : "london"} , { "city" : "barcelona" }]

list.forEach(function(city,i) { city.distance = distance[i] })

console.log(list)

If you need a new Array you can use map:

const distance = [100,200,300]
let list = [ {"city" : "paris"} , {"city" : "london"} , { "city" : "barcelona" }]

let distList = list.map((city,i) => ({ ...city, distance : distance[i]}) )

console.log(distList)

edited Dec 13, 2019 at 9:53

answered Dec 13, 2019 at 9:29

mplungjan

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1 Comment

Saurabh Agrawal Over a year ago

I like your second approach :)

Saurabh Agrawal · Accepted Answer · 2019-12-13 09:29:53Z

3

Try this:

  let array1 = [100, 200, 300]
  let array2 = [{ "city": "paris" }, { "city": "london" }, { "city": "barcelona" }]
  let res = array2.map((value, index) => {
    return { ...value, distance: array1[index] }
  })
  console.log(res);

answered Dec 13, 2019 at 9:29

Saurabh Agrawal

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3 Comments

Saurabh Agrawal Over a year ago

@mplungjan well can do it in both ways, So I preferred create new array instead of modifying existing one.

Prashant Pimpale Over a year ago

(=>) arrow functions are not supported in IE <11!

Saurabh Agrawal Over a year ago

There are some alternatives for the same, so coders will have to take care of it.

Jason · Accepted Answer · 2019-12-13 09:37:41Z

0

const listWithDistances = list.map(
  (item, index) => ({ ...item, distance: distance[index] })
)

This has the same result of your example of returning a new Array of new Objects.

answered Dec 13, 2019 at 9:37

Jason

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Comments

Prashant Pimpale · Accepted Answer · 2019-12-13 09:39:23Z

0

Try this

for(let i = 0; i < distance.length; i++)
{
   list[i].distance = distance[i];
}

edited Dec 13, 2019 at 9:39

Prashant Pimpale

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answered Dec 13, 2019 at 9:29

Shashank

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