What is the reason behind the array.map() function not altering the original array?

I attempted to increment each element of my array by one, but was having trouble. Here is what I tried:

myArray=[1,2,3]
myArray.map(a=>a+=1) // also tried a++ and a=a+1
console.log(myArray) // returns [ 1 , 2 , 3 ]

Unfortunately, this method did not work for me...

So I decided to take a different approach:

myArray=[1,2,3]
mySecondArray=[]
myArray.map(a=>mySecondArray.push(a+1))
console.log(mySecondArray) // returns [ 2, 3, 4 ]

Surprisingly, the second method worked perfectly fine. However, I am still puzzled as to why the first method failed. Can you provide an explanation?

javascriptarrays

Answer №1

Utilizing the map() function in JavaScript enables the creation of a new array by executing a specified function on each item within the original array. This method is considered to be non-mutating, which explains why your initial approach did not yield the expected results.

const myArr = [4, 5, 6];
myArr = myArr.map(y => y * 2);
console.log(myArr);

Answer №2

To revert the values, you can do the following:

myArray = myArray.map(a => a-1);
console.log(myArray)

output --- > [0, 1, 2]

Answer №3

Currently, the instance is not being saved.

Save the instance in an array for later use.

let newArray = [4, 5, 6];
newArray = newArray.map(item => item * 2);
console.log(newArray);

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