Get value from array of array using map javascript

Question

I would like to know how can I get a value from an array of array using map javascript function.

My response from a query :

[ 
    { 
        customer_id: '5d0757aa4b6620003335aff2',
        cars: [ 
            {
                type: 'break', // unique
                serial_number: '0000X523654FE'
                // ... other data, not useful here
            },
            {
                type: 'sport',
                serial_number: '485605FEL45E'
                // ...
            }   
        ]
    }
]

I want to get serial_number string, so here what I did with map javascript function :

const serialNumber = response.items.map(element => {

                    return element.cars.map(car => {
                        if (car.type == "sport") {
                            return car.serial_number;
                        }
                    });
                });

And I get :

[ [ '485605FEL45E' ] ]

I would like to get : '485605FEL45E'

How can remove the double array ? I just want the value.

Thank you very much !

EDIT : I didn't specify something important, type is unique, I can't get two sport cars for the same customer.

you might be after .flat() or .flatMap() if you want to remove the inner array? — Nick Parsons
– Nick Parsons, Commented Aug 9, 2019 at 9:44
If you're removing items from the array, you're going to want to use filter too. — Ben Fortune
– Ben Fortune, Commented Aug 9, 2019 at 9:44
Looking at your want -. '485605FEL45E', this implies your only want 1 single results.. Is this correct, and if so is it just the first it finds.? Multiple results would look like -> ['abc', '123'],... — Keith
– Keith, Commented Aug 9, 2019 at 9:54

Code Maniac · Accepted Answer · 2019-08-09 09:53:16Z

2

You can use find instead

let data = [{
  customer_id: '5d0757aa4b6620003335aff2',
  cars: [{
      type: 'break',
      serial_number: '0000X523654FE'
    },
    {
      type: 'sport',
      serial_number: '485605FEL45E'
    }
  ]
}]

const serialNumber = data.map(element => {
  let found = element.cars.find(car => {
    if (car.type == "sport") {
      return car.serial_number;
    }
  });
  return (found || {}).serial_number
});

console.log(serialNumber)

If there are multiple entries with 'sport' you can use filter instead of find

let data = [{
  customer_id: '5d0757aa4b6620003335aff2',
  cars: [{
      type: 'break',
      serial_number: '0000X523654FE'
    },
    {
      type: 'sport',
      serial_number: '485605FEL45E'
    },
    {
      type: 'sport',
      serial_number: '657445FEL45E'
    }
  ]
}]

const serialNumber = data.map(element => {
  let found = element.cars.reduce((op, car) => {
    if (car.type == "sport") {
      op.push(car.serial_number)
    }
    return op
  }, []);
  return found.length && found
});

console.log(serialNumber.flat())

edited Aug 9, 2019 at 9:53

answered Aug 9, 2019 at 9:46

Code Maniac

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10 Comments

kevinSpaceyIsKeyserSöze Over a year ago

Maybe because OP asked for using map function.

Keith Over a year ago

Not me, but what I would say is that remember find will only return 1 item. What if there are multiple cars that are of type sport.

arizafar Over a year ago

not instead, but should be using find don't understand a downvote.

arizafar Over a year ago

@Keith OP wants to flatten the array so surely there's only one element.

Keith Over a year ago

@AZ_ Not sure why flattening the array should stop the result having multiple serial numbers for multiple sports cars. IOW: If the user is after all sport cars serial number, find will not work. Or do you mean because the OP has put wants -> '485605FEL45E' might need to clarify with OP if he really only wants a single result.

|

GRS · Accepted Answer · 2019-08-09 09:58:26Z

1

You can just use Array.join("").

let items = [{
  customer_id: '5d0757aa4b6620003335aff2',
  cars: [{
      type: 'break',
      serial_number: '0000X523654FE'
    },
    {
      type: 'sport',
      serial_number: '485605FEL45E'
    }
  ]
}]

const serialNumber = items.map(element => {

                return element.cars.map(car => {
                    if (car.type == "sport") {
                        return car.serial_number;
                    }
                });
            });

console.log(serialNumber.join(""));

answered Aug 9, 2019 at 9:58

GRS

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1 Comment

Joe Allen Over a year ago

I accept this answer because with the join function I get exactly what I want : 'value'. Thank you very much

MH2K9 · Accepted Answer · 2019-08-09 09:54:11Z

0

Try using find()

let no;
[
    {
        customer_id: '5d0757aa4b6620003335aff2',
        cars: [
            {
                type: 'break',
                serial_number: '0000X523654FE'
            },
            {
                type: 'sport',
                serial_number: '485605FEL45E'
            }
        ]
    }
]
.find(element => { return element.cars.find(i => !!(i.type === 'sport' && (no = i.serial_number))) })

console.log(no)

answered Aug 9, 2019 at 9:54

MH2K9

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Comments

Fraction · Accepted Answer · 2019-08-09 09:57:52Z

0

You can use Array.find() like this:

const response = [{
  customer_id: '5d0757aa4b6620003335aff2',
  cars: [{
      type: 'break',
      serial_number: '0000X523654FE'
      // ... other data, not useful here
    },
    {
      type: 'sport',
      serial_number: '485605FEL45E'
      // ...
    }
  ]
}]

let serialNumber = null;

response.find(element => {
  return element.cars.find(car => {
    if (car.type == "sport") {
      serialNumber = car.serial_number;
      return true;
    }
  });
});

console.log(serialNumber);

answered Aug 9, 2019 at 9:57

Fraction

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Comments

arizafar · Accepted Answer · 2019-08-09 10:06:12Z

0

Use Array.prototype.find on cars array as following and return the serialNumber to outer map

let data = [{
	customer_id: '5d0757aa4b6620003335aff2',
	cars: [{
		type: 'break',
		serial_number: '0000X523654FE'
	},
	{
		type: 'sport',
		serial_number: '485605FEL45E'
	}
	]
},
{
	customer_id: '5d0757aa4b6620003335aff2',
	cars: [{
		type: 'break',
		serial_number: '0000X523654FE'
	},
	{
		type: 'sport',
		serial_number: '485605FEL45E'
	}
	]
}]


let out = data.map(({cars}) => cars.find(e => e.type === 'sport').serial_number);
console.log(out)

answered Aug 9, 2019 at 10:06

arizafar

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