Javascript - add a new key/value based on another existing key/value for each javascript object inside an array

Question

I have an array of javascript objects (of undefinite length).

var records =
[ 
  { query_result_id: 373,
    url: 'https://www.example1.com/hheyue',
    title: 'title1',
    uselesskey3: 'yo', 
    uselesskey4: 'ya',     
    max_email_nb_sent: 1 },
 { query_result_id: 375,
  url: 'https://www.example2.com',
  title: 'title2',
  uselesskey3: 'yo', 
  uselesskey4: 'ya',     
  max_email_nb_sent: null } 
 //and so on...]

I am today creating a new object called parametersObj (to keep records unchanged for immutability reasons) based on records by doing a certain number of things:

var parametersObj = records
      //remove useless keys      
      .map(({
        title,uselesskey3, uselesskey4, max_email_nb_sent,
        ...item
      }) => item)
      //add new needed keys
      .map(s => (
        {
          ...s,
          status: process.env.CONTEXT === "production" ? "prod" : "dev",
          triggered_at: new Date().toLocaleString()
        }
      ));

This works perfectly.

But what I am trying to do now is to add on the code above when I create parametersObj a method where before removing useless keys (the first .map above), I add a new key called email_nb for each javascript object which is equal either to :

0 if max_email_nb_sent is null
max_email_nb_sent + 1 if max_email_nb_sent is not null

The expected value of parametersObj after we execute the script should be:

[ 
  { query_result_id: 373,
    url: 'https://www.example1.com/hheyue',
    title: 'title1',
    email_nb: 2,
    status: "prod",
    triggered_at: '2019-9-30 23:11:12'   
  },
 { query_result_id: 375,
  url: 'https://www.example2.com',
  title: 'title2',
  email_nb: 0,
  status: "prod",
  triggered_at: '2019-9-30 23:11:12' } 
 //and so on...]

I can use ES6 and prefer to if possible as usually more concise.

I tried this but this below did not work

var parametersObj = records
          //adding the new key email_nb          
         .map(s=> s["email_nb"] = s["max_email_nb_sent"] + 1)
         //remove useless keys      
          .map(({
            title,uselesskey3, uselesskey4, max_email_nb_sent,
            ...item
          }) => item)
          //add new needed keys
          .map(s => (
            {
              ...s,
              status: process.env.CONTEXT === "production" ? "prod" : "dev",
              triggered_at: new Date().toLocaleString()
            }
          ));

but then parametersObj is becoming just equal to [1, 1] which is very wrong...

Feedback on some answers

Tried:

var parametersObj = records
              //adding the new key email_nb          
             .map(item => 
               { ...item, 
                email_nb: item.max_email_nb_sent ? 
                item.max_email_nb_sent + 1 : 0
               }
             )

             //remove useless keys      
              .map(({
                title,uselesskey3, uselesskey4, max_email_nb_sent,
                ...item
              }) => item)
              //add new needed keys
              .map(s => (
                {
                  ...s,
                  status: process.env.CONTEXT === "production" ? "prod" : "dev",
                  triggered_at: new Date().toLocaleString()
                }
              ));

but I get error:

Uncaught SyntaxError: Unexpected token ...

Nikhil · Accepted Answer · 2019-10-01 00:29:46Z

1

The problem with your code is you are returning an object with only email_nb property. You have to return other existing properties as well.

var parametersObj = records    
     .map(item => ({ ...item,
        "email_nb": item.max_email_nb_sent ? item.max_email_nb_sent + 1 : 0
      }))
     .map(
       //remove useless keys      
     )     
     .map(s => (
       //add new needed keys
     ));

Live Example:

var records = [{
    query_result_id: 373,
    url: 'https://www.example1.com/hheyue',
    title: 'title1',
    uselesskey3: 'yo',
    uselesskey4: 'ya',
    max_email_nb_sent: 1
  },
  {
    query_result_id: 375,
    url: 'https://www.example2.com',
    title: 'title2',
    uselesskey3: 'yo',
    uselesskey4: 'ya',
    max_email_nb_sent: null
  }
];

var parametersObj = records
  .map(item => ({ ...item,
    "email_nb": item.max_email_nb_sent ? item.max_email_nb_sent + 1 : 0
  }))

console.log(parametersObj);

edited Oct 1, 2019 at 0:29

answered Oct 1, 2019 at 0:12

Nikhil

6,68110 gold badges36 silver badges74 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Mathieu Over a year ago

I tried but I get Uncaught SyntaxError: Unexpected token ...

Nikhil Over a year ago

Can you post the complete error code? Also update your question with records data you are using.

Mathieu Over a year ago

Sure but I simply copy pasted the block .map you suggested and added to my current query...

Mathieu Over a year ago

Just added it now

Nikhil Over a year ago

@Mathieu - Check out my edited answer and try again.

Collectives™ on Stack Overflow

Javascript - add a new key/value based on another existing key/value for each javascript object inside an array

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related