Determine the quantity of particular information within an array of objects

Question

Determine the quantity of particular information within an array of objects

My goal is to calculate the total number of entries based on the color provided by the user. For instance, if the user enters 'red', the program should return 11. I attempted to achieve this but encountered an issue with the variable cnt not being defined after the loop.

let description=[
                {color:'red',qty:6,remarks:'asdf'},
                {color:'green',qty:5,remarks:'asdf'},
                {color:'red',qty:5,remarks:'asdf'},                             
                {color:'yellow',qty:5,remarks:'asdf'},                         
                {color:'blue',qty:5,remarks:'asdf'},                           
                {color:'white',qty:5,remarks:'asdf'}
                ];
{description.map((t,index) =>{
         let cnt=0;
         if(t.color=='red'){
            cnt=cnt+parseInt(t.qty);    
         }
         console.log(cnt);
      }   
      )}
 console.log(cnt);

javascript arrays dictionary

Answer 1

Answer №1

The issue in your code lies in the initialization of let cnt=0; within the function, causing it to reset on each iteration and therefore not properly adding up the values.

To resolve this, you can utilize the reduce method to check if the color matches colorToSearch and then accumulate the quantity value accordingly.

let items=[
     {color:'red',qty:6,remarks:'asdf'},
     {color:'green',qty:5,remarks:'asdf'},
     {color:'red',qty:5,remarks:'asdf'},                             
     {color:'yellow',qty:5,remarks:'asdf'},                         
     {color:'blue',qty:5,remarks:'asdf'},                           
     {color:'white',qty:5,remarks:'asdf'}
];

let colorToFind = 'red';

let totalQuantity = items.reduce((acc, val) => val.color === colorToFind ? acc + val.qty : acc, 0)

console.log(totalQuantity);

Answer 2

The issue in your code lies in the initialization of let cnt=0; within the function, causing it to reset on each iteration and therefore not properly adding up the values.

To resolve this, you can utilize the reduce method to check if the color matches colorToSearch and then accumulate the quantity value accordingly.

let items=[
     {color:'red',qty:6,remarks:'asdf'},
     {color:'green',qty:5,remarks:'asdf'},
     {color:'red',qty:5,remarks:'asdf'},                             
     {color:'yellow',qty:5,remarks:'asdf'},                         
     {color:'blue',qty:5,remarks:'asdf'},                           
     {color:'white',qty:5,remarks:'asdf'}
];

let colorToFind = 'red';

let totalQuantity = items.reduce((acc, val) => val.color === colorToFind ? acc + val.qty : acc, 0)

console.log(totalQuantity);

Answer 3

Answer №2

To simplify the array, first filter it and then use reduce as shown below

let items=[
                {name:'apple',quantity:6,category:'fruit'},
                {name:'banana',quantity:5,category:'fruit'},
                {name:'orange',quantity:5,category:'fruit'},                             
                {name:'carrot',quantity:5,category:'vegetable'},                         
                {name:'potato',quantity:5,category:'vegetable'},                           
                {name:'tomato',quantity:5,category:'vegetable'}
                ];
                
 let totalFruits=items.filter(item => item.category === 'fruit').reduce(function(sum, current) {
                 return sum + (parseInt(current.quantity) || 0);},0)
 console.log(totalFruits);

Answer 4

To simplify the array, first filter it and then use reduce as shown below

let items=[
                {name:'apple',quantity:6,category:'fruit'},
                {name:'banana',quantity:5,category:'fruit'},
                {name:'orange',quantity:5,category:'fruit'},                             
                {name:'carrot',quantity:5,category:'vegetable'},                         
                {name:'potato',quantity:5,category:'vegetable'},                           
                {name:'tomato',quantity:5,category:'vegetable'}
                ];
                
 let totalFruits=items.filter(item => item.category === 'fruit').reduce(function(sum, current) {
                 return sum + (parseInt(current.quantity) || 0);},0)
 console.log(totalFruits);

Answer 5

Answer №3

To implement the functionality using Array.prototype.reduce(), you can follow this example:

const data=[
  {name:'apple',quantity:6,price:2.5},
  {name:'banana',quantity:4,price:1.5},
  {name:'apple',quantity:8,price:2.5},                             
  {name:'orange',quantity:10,price:1.7},                         
  {name:'pear',quantity:5,price:3.2}                           
];
const fruit = 'apple';
const totalQuantity = data.reduce((accumulator, currentItem) => accumulator + (currentItem.name === fruit ? currentItem.quantity : 0), 0);

console.log(totalQuantity);

Answer 6

To implement the functionality using Array.prototype.reduce(), you can follow this example:

const data=[
  {name:'apple',quantity:6,price:2.5},
  {name:'banana',quantity:4,price:1.5},
  {name:'apple',quantity:8,price:2.5},                             
  {name:'orange',quantity:10,price:1.7},                         
  {name:'pear',quantity:5,price:3.2}                           
];
const fruit = 'apple';
const totalQuantity = data.reduce((accumulator, currentItem) => accumulator + (currentItem.name === fruit ? currentItem.quantity : 0), 0);

console.log(totalQuantity);

Answer 7

Answer №4

The variable ctn is being redefined within each iteration and only exists within the scope of your .map function. This is why you are receiving an error stating "The variable cnt is not defined" after the loop finishes.

To resolve this issue, simply move the declaration of ctn outside of the .map function:

let description=[
                {color:'red',qty:6,remarks:'asdf'},
                {color:'green',qty:5,remarks:'asdf'},
                {color:'red',qty:5,remarks:'asdf'},                             
                {color:'yellow',qty:5,remarks:'asdf'},                         
                {color:'blue',qty:5,remarks:'asdf'},                           
                {color:'white',qty:5,remarks:'asdf'}
                ];
                
let cnt=0;    

description.map((t,index) => {
         if(t.color=='red'){
            cnt=cnt+parseInt(t.qty); //Note: parseInt() isn't needed if qty is always a number
         }
      });
      
 console.log(cnt);

Answer 8

The variable ctn is being redefined within each iteration and only exists within the scope of your .map function. This is why you are receiving an error stating "The variable cnt is not defined" after the loop finishes.

To resolve this issue, simply move the declaration of ctn outside of the .map function:

let description=[
                {color:'red',qty:6,remarks:'asdf'},
                {color:'green',qty:5,remarks:'asdf'},
                {color:'red',qty:5,remarks:'asdf'},                             
                {color:'yellow',qty:5,remarks:'asdf'},                         
                {color:'blue',qty:5,remarks:'asdf'},                           
                {color:'white',qty:5,remarks:'asdf'}
                ];
                
let cnt=0;    

description.map((t,index) => {
         if(t.color=='red'){
            cnt=cnt+parseInt(t.qty); //Note: parseInt() isn't needed if qty is always a number
         }
      });
      
 console.log(cnt);

Answer 9

Answer №5

To solve this issue, you can utilize either the array filter or array reduce method. Below is an illustration using the array reduce method.

Within your program, let cnt=0; is placed inside the map function. Consequently, the value of cnt will not be accessible in the second console.log statement.

let information = [{
    color: 'red',
    qty: 6,
    remarks: 'asdf'
  },
  {
    color: 'green',
    qty: 5,
    remarks: 'asdf'
  },
  {
    color: 'red',
    qty: 5,
    remarks: 'asdf'
  },
  {
    color: 'yellow',
    qty: 5,
    remarks: 'asdf'
  },
  {
    color: 'blue',
    qty: 5,
    remarks: 'asdf'
  },
  {
    color: 'white',
    qty: 5,
    remarks: 'asdf'
  }
];

function getTotal(matchedColor) {
  return information.reduce(function(accumulator, current) {
    // Verify if the color matches the supplied parameter
    if (current.color === matchedColor) {
      accumulator += current.qty; // Add to the previous total
    };
    return accumulator;
  }, 0); // The initial value starts at zero for the sum
}
console.log(getTotal('red'));

Answer 10

To solve this issue, you can utilize either the array filter or array reduce method. Below is an illustration using the array reduce method.

Within your program, let cnt=0; is placed inside the map function. Consequently, the value of cnt will not be accessible in the second console.log statement.

let information = [{
    color: 'red',
    qty: 6,
    remarks: 'asdf'
  },
  {
    color: 'green',
    qty: 5,
    remarks: 'asdf'
  },
  {
    color: 'red',
    qty: 5,
    remarks: 'asdf'
  },
  {
    color: 'yellow',
    qty: 5,
    remarks: 'asdf'
  },
  {
    color: 'blue',
    qty: 5,
    remarks: 'asdf'
  },
  {
    color: 'white',
    qty: 5,
    remarks: 'asdf'
  }
];

function getTotal(matchedColor) {
  return information.reduce(function(accumulator, current) {
    // Verify if the color matches the supplied parameter
    if (current.color === matchedColor) {
      accumulator += current.qty; // Add to the previous total
    };
    return accumulator;
  }, 0); // The initial value starts at zero for the sum
}
console.log(getTotal('red'));

Answer 11

Answer №6

In my opinion, the use of filter followed by reduce to calculate the total quantity is a more clear and concise approach.

let items = [
  {name:'apple',quantity:10},
  {name:'banana',quantity:15},
  {name:'orange',quantity:20},                             
  {name:'kiwi',quantity:12},                         
  {name:'pear',quantity:8},                           
];
let totalQuantity = items.filter(item => item.name !== 'banana').reduce((prev, {quantity}) => prev + quantity, 0);
console.log(totalQuantity);

Answer 12

In my opinion, the use of filter followed by reduce to calculate the total quantity is a more clear and concise approach.

let items = [
  {name:'apple',quantity:10},
  {name:'banana',quantity:15},
  {name:'orange',quantity:20},                             
  {name:'kiwi',quantity:12},                         
  {name:'pear',quantity:8},                           
];
let totalQuantity = items.filter(item => item.name !== 'banana').reduce((prev, {quantity}) => prev + quantity, 0);
console.log(totalQuantity);

Determine the quantity of particular information within an array of objects

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

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