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:

1. If product 1, output you have 2 One Plus
2. 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?

• Andreas: JSON is always a string.
• adiga: Why are you doing JSON.stringify(obj) as key instead of just using obj.Brand
• Brad: @user4642212 Is there a reason you rolled back that edit? It's quite clear that string isn't the keyword here.
• Sebastian Simon: @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.
• Heretic Monkey: 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.

Answer 1

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));

Answer 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));

Answer 3

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 ")
}`
);

• Ibraheem: @gyohza indeed! Beat me to it! But check your return value in your reduction?
• gyohza: You mean this bit (acc[val.Brand] || 0) + 1? Yep, it's actually the exact same expression. :P
• gyohza: Actually it's a quite standard answer, so it's no wonder both are so alike.
• Ibraheem: @gyohza I meant returning acc after the comma, a neat JS shorthand I’ve forgotten about! Thanks!
• gyohza: 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.

Answer 4

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"
 }
]));

Answer 5

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));