Introducing a fresh addition to the array

Question

Introducing a fresh addition to the array

I am looking for a way to create a new array without modifying the original one. Currently, there is a function that adds a new object to an existing array, but I need a different method to achieve this. Can someone suggest a solution?

const arr = [
   {  
     "name":"BMW",
     "price":"55 000",
     "country":"Germany",
     "certificate":"yes"
  },
  {  
    "name":"Mitsubishi",
    "price":"93 000", 
    "constructor":"Bar John",
    "door":"3",
    "country":"Japan",
  },
  {  
    "name":"TOYOTA", 
    "price":"48 000", 
    "max_people":"7",
    "country":"Japan",
    "certificate":"yes"
  },
  {  
    "name":"Volkswagen",
    "price":"36 000", 
    "constructor":"Pier Sun",
    "country":"Germany",
    "certificate":"no"
  },
 ];
function pushArr (arr, item){
    arr.push(item); 
}

let Cars = pushArr(arr,{  
  "name":"Audi",
  "price":"89 000", 
  "constructor":"Hubert Trumpius",
  "country":"Germany",
  "certificate":"yes"
});

console.log(arr);

javascript arrays methods

Answer 1

Answer №1

If you're looking to combine arrays in JavaScript, you have a couple of options - you can either use Array.concat() or employ the spread syntax:

function mergeArrays(firstArray, secondArray) {
  return firstArray.concat(secondArray); // or simply: [...firstArray, ...secondArray]
}

const firstArray = [{"name":"BMW","price":"55 000","country":"Germany","certificate":"yes"},{"name":"Mitsubishi","price":"93 000","constructor":"Bar John","door":"3","country":"Japan"},{"name":"TOYOTA","price":"48 000","max_people":"7","country":"Japan","certificate":"yes"},{"name":"Volkswagen","price":"36 000","constructor":"Pier Sun","country":"Germany","certificate":"no"}];

let combinedArray = mergeArrays(firstArray, {
  "name": "Audi",
  "price": "89 000",
  "constructor": "Adolf Trump",
  "country": "Germany",
  "certificate": "yes"
});

console.log(firstArray === combinedArray);
console.log(combinedArray);

Answer 2

If you're looking to combine arrays in JavaScript, you have a couple of options - you can either use Array.concat() or employ the spread syntax:

function mergeArrays(firstArray, secondArray) {
  return firstArray.concat(secondArray); // or simply: [...firstArray, ...secondArray]
}

const firstArray = [{"name":"BMW","price":"55 000","country":"Germany","certificate":"yes"},{"name":"Mitsubishi","price":"93 000","constructor":"Bar John","door":"3","country":"Japan"},{"name":"TOYOTA","price":"48 000","max_people":"7","country":"Japan","certificate":"yes"},{"name":"Volkswagen","price":"36 000","constructor":"Pier Sun","country":"Germany","certificate":"no"}];

let combinedArray = mergeArrays(firstArray, {
  "name": "Audi",
  "price": "89 000",
  "constructor": "Adolf Trump",
  "country": "Germany",
  "certificate": "yes"
});

console.log(firstArray === combinedArray);
console.log(combinedArray);

Answer 3

Answer №2

The reason behind this behavior is that JavaScript objects, which also include arrays, are passed by reference, while scalar values are passed by value.

When you pass objects to functions and directly modify them, you are essentially working with the same object in memory.

To prevent unintentional mutations of your object, it's important to create a new instance of the object before making any changes. There are several methods to achieve this:

Using destructuring or spreading your parameter like function({...f}, t)
Utilizing Object.assign()
Assigning f within your function to a destructured version of f (f = {...f};)

const arr = [{
    "name": "BMW",
    "price": "55 000",
    "country": "Germany",
    "certificate": "yes"
  },
  {
    "name": "Mitsubishi",
    "price": "93 000",
    "constructor": "Bar John",
    "door": "3",
    "country": "Japan",
  },
  {
    "name": "TOYOTA",
    "price": "48 000",
    "max_people": "7",
    "country": "Japan",
    "certificate": "yes"
  },
  {
    "name": "Volkswagen",
    "price": "36 000",
    "constructor": "Pier Sun",
    "country": "Germany",
    "certificate": "no"
  },
];

//destructure your argument here 
function pushArr([...arr], item) {
  return [arr, item];
}

let Cars = pushArr(arr, {
  "name": "Audi",
  "price": "89 000",
  "constructor": "Adolf Trump",
  "country": "Germany",
  "certificate": "yes"
});

console.log(arr);
console.log(Cars);

It's crucial to remember that re-assigning your object will not update its value. For more details on this concept, refer to Call by sharing.

Answer 4

The reason behind this behavior is that JavaScript objects, which also include arrays, are passed by reference, while scalar values are passed by value.

When you pass objects to functions and directly modify them, you are essentially working with the same object in memory.

To prevent unintentional mutations of your object, it's important to create a new instance of the object before making any changes. There are several methods to achieve this:

Using destructuring or spreading your parameter like function({...f}, t)
Utilizing Object.assign()
Assigning f within your function to a destructured version of f (f = {...f};)

const arr = [{
    "name": "BMW",
    "price": "55 000",
    "country": "Germany",
    "certificate": "yes"
  },
  {
    "name": "Mitsubishi",
    "price": "93 000",
    "constructor": "Bar John",
    "door": "3",
    "country": "Japan",
  },
  {
    "name": "TOYOTA",
    "price": "48 000",
    "max_people": "7",
    "country": "Japan",
    "certificate": "yes"
  },
  {
    "name": "Volkswagen",
    "price": "36 000",
    "constructor": "Pier Sun",
    "country": "Germany",
    "certificate": "no"
  },
];

//destructure your argument here 
function pushArr([...arr], item) {
  return [arr, item];
}

let Cars = pushArr(arr, {
  "name": "Audi",
  "price": "89 000",
  "constructor": "Adolf Trump",
  "country": "Germany",
  "certificate": "yes"
});

console.log(arr);
console.log(Cars);

It's crucial to remember that re-assigning your object will not update its value. For more details on this concept, refer to Call by sharing.

Answer 5

Answer №3

If you want to duplicate an array, try using the slice function.

function addToArray(arr, item) {
    let clone = arr.slice();
    clone.push(item);
    return clone;
}

Answer 6

If you want to duplicate an array, try using the slice function.

function addToArray(arr, item) {
    let clone = arr.slice();
    clone.push(item);
    return clone;
}

Introducing a fresh addition to the array

Answer №1

Answer №2

Answer №3

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