How can you determine the number of elements that match in two arrays?

Question

How can you determine the number of elements that match in two arrays?

As a coding newbie, I'm looking to create a JavaScript function that compares two arrays and assigns a score based on the number of matching elements. However, when I attempt to run it in Chrome's console, I receive an error message stating that "compare is not defined."

let score = 0;
function compare(arr1, arr2) {
    for (let i = 0; i < arr2.length; i++) {
        for (let j = 0; j < arr1.length; j++) {
            if(arr1[j] === arr2[i]){
                score++;
            }   
        }
    }
}

javascript arrays compare

Answer 1

Answer №1

If you want to determine the count of matched elements, you can utilize the .reduce() method:

let arr1 = [1, 2, 3, 4, 5],
    arr2 = [3, 4, 5, 6, 7],
    compare = (a1, a2) => arr1.reduce((a, c) => a + arr2.includes(c), 0);

console.log(compare(arr1, arr2));

Another approach is to use .filter() to create an array of matched elements and then get its length for the count.

let arr1 = [1, 2, 3, 4, 5],
    arr2 = [3, 4, 5, 6, 7],
    compare = (a1, a2) => arr1.filter(v => arr2.includes(v)).length;

console.log(compare(arr1, arr2));

Additional Resources:

Answer 2

If you want to determine the count of matched elements, you can utilize the .reduce() method:

let arr1 = [1, 2, 3, 4, 5],
    arr2 = [3, 4, 5, 6, 7],
    compare = (a1, a2) => arr1.reduce((a, c) => a + arr2.includes(c), 0);

console.log(compare(arr1, arr2));

Another approach is to use .filter() to create an array of matched elements and then get its length for the count.

let arr1 = [1, 2, 3, 4, 5],
    arr2 = [3, 4, 5, 6, 7],
    compare = (a1, a2) => arr1.filter(v => arr2.includes(v)).length;

console.log(compare(arr1, arr2));

Additional Resources:

Answer 3

Answer №2

Here is a solution that should meet your needs:

Your requested code update :

let numbers1 = [2, 5, 8, 10];
let numbers2 = [2, 4, 6, 8, 10];
function compare(numbers1,numbers2){
  let matches=0;
  const maxLength=numbers1.length>numbers2.length ? numbers2.length : numbers1.length;
  for(let j=0;j<maxLength;j++){
    if(numbers1[j]==numbers2[j]){
      matches++;
    }
  }
  return matches;
}
console.log(compare(numbers1,numbers2));

Answer 4

Here is a solution that should meet your needs:

Your requested code update :

let numbers1 = [2, 5, 8, 10];
let numbers2 = [2, 4, 6, 8, 10];
function compare(numbers1,numbers2){
  let matches=0;
  const maxLength=numbers1.length>numbers2.length ? numbers2.length : numbers1.length;
  for(let j=0;j<maxLength;j++){
    if(numbers1[j]==numbers2[j]){
      matches++;
    }
  }
  return matches;
}
console.log(compare(numbers1,numbers2));

How can you determine the number of elements that match in two arrays?

Answer №1

Answer №2

Your requested code update :

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