Create a string from object array

Question

I have two arrays as below:

var product1 = [
    {
      "Brand": "One Plus"
    },
    {
      "Brand": "One Plus"
    }
  ];
var product2 = [
    {
      "Brand": "One Plus"
    },
    {
      "Brand": "Apple"
    }
  ];

I want to loop through the array and print the following:

If product 1, output you have 2 One Plus
If product 2, output you have 1 One Plus and 1 Apple

Below is the code that I tried.

var product1 = [
    {
      "Brand": "One Plus"
    },
    {
      "Brand": "One Plus"
    }
  ];
var product2 = [
    {
      "Brand": "One Plus"
    },
    {
      "Brand": "Apple"
    }
  ];

counter1 = {}
product1.forEach(function(obj) {
    var key = JSON.stringify(obj)
    counter1[key] = (counter1[key] || 0) + 1
});
console.log(counter1);
counter2 = {}
product2.forEach(function(obj) {
    var key = JSON.stringify(obj)
    counter2[key] = (counter2[key] || 0) + 1
});
console.log(counter2);

I’m able to get the JSON output, but how can I get it in the sentence format?

Why are you doing JSON.stringify(obj) as key instead of just using obj.Brand — adiga
– adiga, Commented Jun 2, 2020 at 17:56
@user4642212 Is there a reason you rolled back that edit? It's quite clear that string isn't the keyword here. — Brad
– Brad, Commented Jun 2, 2020 at 17:57
@Brad I didn’t roll back the edit, I edited at the same time and looked back into the revision history to reapply your changes. It’s faster than to start from scratch. — Sebastian Simon
– Sebastian Simon, Commented Jun 2, 2020 at 17:59
I wouldn't use JSON at all. Just group and count: Group array of objects by value and get count of the groups, then reduce the keys and counts. — Heretic Monkey
– Heretic Monkey, Commented Jun 2, 2020 at 18:04

gyohza · Accepted Answer · 2020-06-02 18:43:42Z

5

How about this?

var product1 = [{
    "Brand": "One Plus"
  },
  {
    "Brand": "One Plus"
  }
];
var product2 = [{
    "Brand": "One Plus"
  },
  {
    "Brand": "Apple"
  }
];

function countProducts(arr) {
  let counter = arr.reduce((acc, val) =>
    (acc[val.Brand] = (acc[val.Brand] || 0) + 1, acc), {});
  let strings = Object.keys(counter).map(k => `${counter[k]} ${k}`);
  return `You have ${strings.join(' and ')}`;
}

console.log(countProducts(product1));

console.log(countProducts(product2));

edited Jun 2, 2020 at 18:43

answered Jun 2, 2020 at 18:08

gyohza

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Comments

Chase · Accepted Answer · 2020-06-02 18:13:21Z

2

const product1 = [
  {Brand: "One Plus"},
  {Brand: "One Plus"},
];
const product2 = [
  {Brand: "One Plus"},
  {Brand: "Apple"},
];

function whatYouHaveIn(list) {
  return `You have ` + Object.entries(list.reduce((a, c) => {
    a[c.Brand] = a[c.Brand] || 0;
    a[c.Brand]++;
    return a;
  }, {})).map(([brand, count]) => `${count} ${brand}`).join(` and `);
}

console.log(whatYouHaveIn(product1));

console.log(whatYouHaveIn(product2));

answered Jun 2, 2020 at 18:13

Chase

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Comments

Sebastian Simon · Accepted Answer · 2020-06-02 18:14:59Z

2

const product1s = product1.reduce((acc, product) => {
acc[product.Brand] = (acc[product.Brand] || 0) + 1;
return acc;
}, {});

console.log(
`You have ${
Object.keys(product1s).map(product => `${product1s[product]} ${product}`).join(" and ")
}`
);

edited Jun 2, 2020 at 18:14

Sebastian Simon

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answered Jun 2, 2020 at 18:11

Ibraheem

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6 Comments

Ibraheem Over a year ago

@gyohza indeed! Beat me to it! But check your return value in your reduction?

gyohza Over a year ago

You mean this bit (acc[val.Brand] || 0) + 1? Yep, it's actually the exact same expression. :P

gyohza Over a year ago

Actually it's a quite standard answer, so it's no wonder both are so alike.

Ibraheem Over a year ago

@gyohza I meant returning acc after the comma, a neat JS shorthand I’ve forgotten about! Thanks!

gyohza Over a year ago

Oh! Yeah. That is different between our codes, it seems. The comma operator was just syntactic sugar though - it's easier on the eyes not to have to create a new block for the function body.

|

on8tom · Accepted Answer · 2020-06-02 18:16:30Z

0

You first have to count the occurances, than its just a matter of string concat or templates

function strinify(a) {
  let occurances = {};
  
  a.forEach(function(e,i){
   if( e.Brand in occurances ) {
    occurances[e.Brand] ++;
   } else {
    occurances[e.Brand] = 1;
   }
  });
   
  let str = [];
  
  for( brand in occurances ){
    count = occurances[brand];
    str.push(count + " " + brand);
  }; 
  
  return "you have " + str.join(" and ");
}
  
console.log(strinify([
    {
      "Brand": "One Plus"
    },
    {
      "Brand": "One Plus"
    },
    {
      "Brand": "Apple"
    }
]));

answered Jun 2, 2020 at 18:16

on8tom

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Comments

Jens Ingels · Accepted Answer · 2020-06-02 21:01:08Z

const order1 = [
  {
    "Brand": "One Plus",
    "test" : "test"
  },
  {
    "Brand": "One Plus"
  },
  {
  	"Bar": "Foo"
  }
];
const order2 = [
  {
    "Brand": "One Plus"
  },
  {
    "Brand": "Apple"
  }
];

const orderToString = (order) => {
  if(order == null) return;
  
  const productsWithBrand = order.filter(product => Object.keys(product).includes('Brand'));
  const productBrandCounter = (counter, product) => (counter[product.Brand] = (counter[product.Brand] || 0) + 1, counter);
  const countPerProduct = productsWithBrand.reduce(productBrandCounter, {});
  const stringPerProduct = Object.keys(countPerProduct).map(brand => `${countPerProduct[brand]} ${brand}`);

  return `You have ${stringPerProduct.join(' and ')}`;
}

console.log(orderToString(order1));

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