CODEWITHSUNDEEP
javascriptarraysfor-loopreturn
E McGill
E McGill

Reputation: 147

How to find the largest number in an object using a for loop?

Here is my dataset:

let items = [
  {
    itemName: "Effective Programming Habits",
    type: "book",
    price: 13.99
  },
  {
    itemName: "Creation 3005",
    type: "computer",
    price: 299.99
  },
  {
    itemName: "Finding Your Center",
    type: "book",
    price: 15.00
  }
]

I'm trying to find and return the largest number in this object using a for loop. I know there are probably easier, more efficient routes but I'm specifically working on for loops.

Instead of simply returning the largest price, I however want to return the itemName of the largest price item. My code currently is only returning the largest price: 299.99 and not the itemName "Creation 3005". How would I return this information using for loops? This is what I have so far.

function mostExpensiveItemName(items) {
  let expensive = items[0].price || null; 
  let number = null;
  let name = null;
  for (let i = 0; i < items.length; i++) {
    number = items[i].price;
    expensive = Math.max(expensive, number); 
    }
   return expensive;
  }

Upvotes: 1

Views: 949

Answers (6)

eyooo son
eyooo son

Reputation: 16

function mostExpensiveItemName(items) {
   let expensive = items[0]; 
   let number = null;
   let name = null;
   for (let i = 0; i < items.length; i++) {
      number = items[i];
      expensive = expensive.price < number.price ? number:;
   }
   return expensive;
}

Upvotes: 0

Nicholas Carey
Nicholas Carey

Reputation: 74315

I would do something like this. It's cleaner, more expressive and you're not conflating two different concerns:

  • finding the most expensive item, and
  • determining its name
function mostExpensiveItemName(items) {
  let item = mostExpensiveItem(items);
    return item ? item.Name : undefined;
}

function mostExpensiveItem(items) {
  let max;

  for ( const item of items ) {
     max = !item                  ? item   // 1st item in list
         : item.price > max.price ? item   // replace existing w/new most-expensive item
         :                          max  ; // keep existing
  }

  return max ;
}

Upvotes: 0

Alex Mckay
Alex Mckay

Reputation: 3706

If you decide to look at alternatives to for loops, these sort of questions are incredibly easy using reduce.

const selectHigherPrice = (state, item) => state.price > item.price ? state : item

const initialState = items[0]

items.reduce(selectHigherPrice, initialState)

// One line
items.reduce((state, item) => state.price > item.price ? state : item)
  • state is initialised as the first item in the items list
  • The selectHigherPrice function is called for each item in the array
  • If the current state.price property is greater than the item.price property:
    • state is returned
    • otherwise item is returned and becomes the state variable when selectHigherPrice is called for the next item in the list.

If you are sure your list will have items you can omit the second argument

Upvotes: 1

StackSlave
StackSlave

Reputation: 10617

Here's what I would do:

function mostExpensive(objArray){
  const m = objArray.map(o=>o.price);
  return objArray[m.indexOf(Math.max(...m))];
}
let items = [
  {
    itemName: "Effective Programming Habits",
    type: "book",
    price: 13.99
  },
  {
    itemName: "Creation 3005",
    type: "computer",
    price: 299.99
  },
  {
    itemName: "Finding Your Center",
    type: "book",
    price: 15.00
  }
];
const me = mostExpensive(items);
console.log(me); console.log(me.price);

Upvotes: 0

Joseph
Joseph

Reputation: 6269

you could use forEach like this

let items = [
  {
    itemName: "Effective Programming Habits",
    type: "book",
    price: 13.99
  },
  {
    itemName: "Creation 3005",
    type: "computer",
    price: 299.99
  },
  {
    itemName: "Finding Your Center",
    type: "book",
    price: 15.00
  }
]

let maxPrice = 0, product;
items.forEach(el => {
  if(el.price > maxPrice){ 
     maxPrice = el.price;
     product = Object.assign({}, el); // for make sure you made a new copy not a reference 
  }
});

console.log(product, maxPrice)

Upvotes: 2

CertainPerformance
CertainPerformance

Reputation: 371019

Reassign the outer variable only if the item you're iterating over has a higher price:

let items = [
  {
    itemName: "Effective Programming Habits",
    type: "book",
    price: 13.99
  },
  {
    itemName: "Creation 3005",
    type: "computer",
    price: 299.99
  },
  {
    itemName: "Finding Your Center",
    type: "book",
    price: 15.00
  }
];
function mostExpensiveItemName(items) {
  let highestPriceSoFar = 0;
  let nameOfHighestPriceSoFar;
  for (const { itemName, price } of items) {
    if (price > highestPriceSoFar) {
      highestPriceSoFar = price;
      nameOfHighestPriceSoFar = itemName;
    }
  }
  console.log(nameOfHighestPriceSoFar);
}
mostExpensiveItemName(items);

Upvotes: 3

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