I would like to find the difference between two arrays by creating a third array that only contains the elements not found in the first array

Question

I would like to find the difference between two arrays by creating a third array that only contains the elements not found in the first array

Subtracting elements from two arrays. arr1=["AT","IN","UK","US"] and arr2=["UK","ZA"]. I want the result to be arr1-arr2 = ["AT","IN","US"]

I have attempted to perform the subtraction of the arrays as described above, but instead of obtaining the correct output, I keep getting arr1[]. Here is the code I used:

var firstArray = ["AT","IN","UK","US"]; 
var secondArray= ["UK","ZA"] ;
var subtractedArray = [];
subtractedArray = firstArray ;

console.log(subtractedArray);
for(i=0;i<firstArray.length;i++)
{
    for(j=0;j<=secondArray.length;j++)
    {
    if (firstArray.includes(secondArray[j]))   
        {
            var index = subtractedArray.indexOf(secondArray[j]);
            if (index > -1) {
                subtractedArray.splice(index, 1);
            }
        }
    }
}

javascript arrays

Answer 1

Answer №1

To eliminate the element in array a that is also present in array b, you can use the filter() method.

Iterate through array a using the filter() method. During each iteration, check if the element in array a is not found in array b. The filter() method will retain the element if the callback function returns true; otherwise, it will remove the current element in the iteration.

const a = ['AT','IN','UK','US'];
const b = ['UK','ZA'];
const r = a.filter(i => b.indexOf(i) === -1)
console.log(r)

Answer 2

To eliminate the element in array a that is also present in array b, you can use the filter() method.

Iterate through array a using the filter() method. During each iteration, check if the element in array a is not found in array b. The filter() method will retain the element if the callback function returns true; otherwise, it will remove the current element in the iteration.

const a = ['AT','IN','UK','US'];
const b = ['UK','ZA'];
const r = a.filter(i => b.indexOf(i) === -1)
console.log(r)

Answer 3

Answer №2

Here's a simple solution:

prevCountries.filter(x => !sectedCountries.includes(x))

Alternatively, for a potentially faster solution utilizing sets for efficient membership test:

let sectedSet = new Set(sectedCountries)
prevCountries.filter(x => !sectedSet.has(x))

Answer 4

Here's a simple solution:

prevCountries.filter(x => !sectedCountries.includes(x))

Alternatively, for a potentially faster solution utilizing sets for efficient membership test:

let sectedSet = new Set(sectedCountries)
prevCountries.filter(x => !sectedSet.has(x))

I would like to find the difference between two arrays by creating a third array that only contains the elements not found in the first array

Answer №1

Answer №2

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