Difference Between indexOf and findIndex function of array

Q: Difference Between indexOf and findIndex function of array

The task is to differentiate between the indexOf() and findIndex() methods of JavaScript. we’re going to discuss both approaches.

What is the difference between find() and filter() methods in JavaScript ?

The task is to differentiate between the indexOf() and findIndex() methods of JavaScript. we’re going to discuss both approaches.

JavaScript indexOf() Method: This method is used to find the index of the first occurrence of the elements provided for search as the argument to the function.

Syntax:

arr.indexOf(element[, index])

Parameters:

element: This parameter specifies the element to be searched.
index: This parameter specifies from which index search to start.

Return value: This method returns the index of the string (0-based) where the search value is found for the first time. If the search value cannot be found in the string then the function returns -1.

JavaScript findIndex() Method: This method returns the index of the first element of the given array which satisfies the testing function.

Syntax:

array.findIndex(fun(curValue, index, arr), thisValue)

Parameters:

fun: This parameter specifies a function to be run for every element of the array.
curValue: This parameter specifies the value of the current element.
index: This parameter specifies the array index of the current element.
arr: This parameter specifies the array object with the current element belongs.
thisValue: This parameter specifies a value to be passed to the function to be used as its “this” value. If this is empty, the value “undefined” will be used.

Return value: It returns the array element index if any of the elements in the array pass the test, otherwise, it returns -1.

Example 1: In this example, indexOf() method is used.

Javascript

let array = ["Beginner", "GFG", "Beginner", "Beginner"];
 
console.log("Array: [" + array + "]");
 
console.log("First index of 'Beginner' is "
    + array.indexOf('Beginner'));

Output

Array: [Beginner,GFG,Beginner,Beginner]
First index of 'Beginner' is 0

Example 2: In this example, findIndex() function is used.

Javascript

let array = [1, 3, 4, 5, 6, 7, 8, 9];
 
console.log("Array: [" + array + "]");
 
function getEven(n) {
    if (n % 2 == 0) {
        return 1;
    }
    return 0;
}
 
console.log("First even number in array is at index "
        + array.findIndex(getEven));

Output

Array: [1,3,4,5,6,7,8,9]
First even number in array is at index 2

Conclusion:

The indexOf() method is used when we want to find the first occurrence of a specified element and the element is known.
The findIndex() method is used when we want to specify a particular condition to that element.
JavaScript indexOf() method takes direct element is specified so it is useful when we are working with array of objects.
JavaScript findIndex() method takes a callback function which returns the value of the element whose index is to be found.

Tags:

#JavaScript #Web Technologies

What is the difference between find() and filter() methods in JavaScript ?