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javascriptarrays
Sanchit Kumar
Sanchit Kumar

Reputation: 45

Find Index where Two Arrays have same Value

If I have two arrays, in Javascript:

let arr1 = ["Dog", "Cat", "Monkey", "Zebra", "Goat", "Goose"];
let arr2 = ["Zebra", "Goat"];

How can I find the indexes of the larger array where there is a match and store them in another array so example output would be:

let indexes = [3,4]

Upvotes: 0

Views: 1361

Answers (3)

Nithish
Nithish

Reputation: 6009

You can achieve the expected output using Array.map and Array.findIndex

let arr1 = ["Dog", "Cat", "Monkey", "Zebra", "Goat", "Goose"];
let arr2 = ["Zebra", "Goat"];

const findIndexes = (param1, param2) => {
  let arr1 = [...param1];
  let arr2 = [...param2];
  //swap the arrays if the no.of array elements 
  //in the second array are greater than first
  if(arr1.length < arr2.length) {
    [arr1, arr2] = [arr2, arr1];
  }
  //Loop through all the items of the smaller array
  //check if the element is present in the bigger array
  return arr2.map(a2 => arr1.findIndex(a1 => a1 === a2));
}

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

//here for "test", we'll get index as -1, because
//if the matching element is not found, findIndex will 
//return -1
let arr3 = ["Cat", "Goose", "test"];
console.log(findIndexes(arr3, arr1));

If you wish to get the indexes of the elements that are found and wish to filter out all the -1s, below is the code for the same.

let arr1 = ["Dog", "Cat", "Monkey", "Zebra", "Goat", "Goose"];
let arr2 = ["Zebra", "Goat"];

const findIndexes = (param1, param2) => {
  let arr1 = [...param1];
  let arr2 = [...param2];
  if(arr1.length < arr2.length) {
    [arr1, arr2] = [arr2, arr1];
  }
  return arr2.map(a2 => arr1.findIndex(a1 => a1 === a2)).filter(ele => ele !== -1);
}

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

let arr3 = ["Cat", "Goose", "test"];
console.log(findIndexes(arr3, arr1));

Upvotes: 1

David Losert
David Losert

Reputation: 4802

You could do it by mapping over your search-teams (arr2) and then using the findIndex Method on the source-array (arr1) like this:

let arr1 = ["Dog", "Cat", "Monkey", "Zebra", "Goat", "Goose"];
let arr2 = ["Zebra", "Goat"];

const result = arr2.map(searchTerm => arr1.findIndex((compareTerm) => compareTerm === searchTerm));

console.log(result);

Upvotes: 1

kdsprogrammer
kdsprogrammer

Reputation: 156

let arr1 = ["Dog", "Cat", "Monkey", "Zebra", "Goat", "Goose"];
let arr2 = ["Zebra", "Goat"];
let indexes = []

arr1.forEach((item, index) => {
  if(arr2.includes(item)){
    indexes.push(index)
  }
})

console.log(indexes)

Upvotes: 0

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