Reducing an array of strings into individual strings using JS

Question

I am trying to reduce an array of strings into individual strings, it works well only if i have one string within each array, but not more than one.

const listItems = [
  {
    sys: {
      type: 'Link',
      linkType: 'Entry',
      id: 'm-list-basic-1'
    }
  },
  {
    sys: {
      type: 'Link',
      linkType: 'Entry',
      id: 'm-list-basic-2'
    }
  },
  {
    sys: {
      type: 'Link',
      linkType: 'Entry',
      id: 'm-list-basic-3'
    }
  }
];

const listIds = listItems.reduce((a, currentValue) =>
            [...a, currentValue.sys.id], [])

// I have also tried `mlistId.toString()`
console.log(...listIds)

Currently i get, for example:

m-list-basic-1 m-list-basic-2 m-list-basic-3 (all on the same line using spread)

m-list-basic-1,m-list-basic-2,m-list-basic-3 (comma'ed using toString()

whereas i want them individual like so:

m-list-basic-1

m-list-basic-2

m-list-basic-3

You are trying to console.log mlistId, but I don't see a variable with that name anywhere? I assume you are trying to console.log listIds — Thomas Bay
– Thomas Bay, Commented Sep 17, 2021 at 22:47
this looks ok to me (although it would be simpler to understand using map rather than reduce). Can you show both the output you want to obtain, and what you actually get, so we can see the problem? — Robin Zigmond
– Robin Zigmond, Commented Sep 17, 2021 at 22:49
So, this is really about printing something into the console?? — Randy Casburn
– Randy Casburn, Commented Sep 17, 2021 at 22:54

Nikola Pavicevic · Accepted Answer · 2021-09-17 23:03:34Z

1

Try with forEach:

const listItems = [
  {
    sys: {
      type: 'Link',
      linkType: 'Entry',
      id: 'm-list-basic-1'
    }
  },
  {
    sys: {
      type: 'Link',
      linkType: 'Entry',
      id: 'm-list-basic-2'
    }
  },
  {
    sys: {
      type: 'Link',
      linkType: 'Entry',
      id: 'm-list-basic-3'
    }
  }
];

const listIds = listItems.reduce((a, currentValue) =>
            [...a, currentValue.sys.id], [])

listIds.forEach(l => console.log(l))

answered Sep 17, 2021 at 23:03

Nikola Pavicevic

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Soc · Accepted Answer · 2021-09-18 00:01:04Z

1

If you're trying to print the id as a new line separated string, you don't need reduce to do this. Instead, you want to use Array.map, combined with String.join with a \n character.

See example below:

const listItems = [
  {
    sys: {
      type: 'Link',
      linkType: 'Entry',
      id: 'm-list-basic-1'
    }
  },
  {
    sys: {
      type: 'Link',
      linkType: 'Entry',
      id: 'm-list-basic-2'
    }
  },
  {
    sys: {
      type: 'Link',
      linkType: 'Entry',
      id: 'm-list-basic-3'
    }
  }
];

console.log(listItems.map(item => item.sys.id).join('\n'));

answered Sep 18, 2021 at 0:01

Soc

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