Lodash _.intersectionBy() Method

Lodash _.intersectionBy() is used to take the intersection of the array with any number of arrays based on some function that iterates over each element of the array. It returns the array after doing the intersection of the arrays.

Syntax:

_.intersectionBy([arrays], [iteratee=_.identity]);

Parameters:

• arrays: It is the array whose intersection has to be taken.
• iteratee=_.identity: It is the function that iterates over each element of the array whose intersection is to be taken.

Return Value:

It returns the array after the intersection with no duplicates.

Example 1: In this example, we are getting the intersection of two arrays by the use of the lodash _.intersectionBy() method.

javascript

// Requiring the lodash library
const _ = require("lodash");

// Original arrays
let array1 = [1, 2, 4, 3, 4, 4]
let array2 = [1, 2, 5, 6]

// Using _.intersectionBy() method
let newArray = _.intersectionBy(array1, array2);

// Printing original Array
console.log("original Array1: ", array1)
console.log("original Array2: ", array2)

// Printing the newArray after intersection
console.log("new Array: ", newArray)

Output:

Example 2: In this example, we are getting the intersection of two arrays and also printing those values only which are closer to Math.ceil by the use of the lodash _.intersectionBy() method.

javascript

// Requiring the lodash library
const _ = require("lodash");

// Original array and array1
// float values are given
let array1 = [1.1, 2.6, 4, 3.2, 1, 2]
let array2 = [1, 2, 3, 5, 6]

// Using _.intersection() method
// when this function is run array1
// looks like array1=[2, 3, 4, 4, 1, 2]
// after that intersection is taken
let newArray = _.intersectionBy(
    array1, array2, Math.ceil);

// Printing original Array
console.log("original Array1: ", array1)
console.log("original Array2: ", array2)

// Printing the newArray
console.log("new Array: ", newArray)

Output:

Example 3: In this example, we are getting the intersection of two arrays by the use of the lodash _.intersectionBy() method. When multiple common elements are present it return them only one times and no duplicates are returned in the array.

javascript

// Requiring the lodash library
const _ = require("lodash");

// Original array
let array1 = ["a", "b", "c", "a"]
let array2 = ["a", "d", "e", "a"]

// Using _.intersection() method
let newArray = _.intersectionBy(
    array1, array2, "a");

// Printing original Array
console.log("original Array1: ", array1)
console.log("original Array2: ", array2)

// Printing the newArray
console.log("new Array: ", newArray)

Output: