Javascript Array some()

// a test function: returns an even number
function isEven(element) {
  return element % 2 === 0;
}

// defining an array
let numbers = [1, 3, 2, 5, 4];

// checks whether the numbers array contain at least one even number
console.log(numbers.some(isEven));

// Output: true 

some() Syntax

The syntax of the some() method is:

arr.some(callback(currentValue), thisArg)

Here, arr is an array.

some() Parameters

The some() method can take two parameters:

• callback - The function to test for each array element. It takes in:
  • currentValue - The current element being passed from the array.
• thisArg (optional) - Value to use as this when executing callback. By default, it is undefined.

some() Return Value

• Returns true if an array element passes the given test function (callback returns a truthy value).
• Otherwise, it returns false.

Example 1: Using some() Method

// a test function: returns age that is less that 18
function checkMinor(age) {
  return age < 18;
}

const ageArray = [34, 23, 20, 26, 12];

// checks whether ageArray contains any element that is less than 18
let check = ageArray.some(checkMinor);

console.log(check);

Output

true

In the above example, we have used the some() method to find out whether any element of the ageArray array contains a value less than 18.

At first, we created the callback function checkMinor() that returns age less than 18.

We have then passed callback to the some() method as ageArray.some(checkMinor) that checks for elements less than 18 and returns true.

Example 2: some() Method to Check Result of Students

// array of scores obtained by student 
let scoreObtained = [45, 50, 39, 78, 65, 20];

// a test function: returns score less than 40
function studentIsPassed(score) {
  return score < 40;
}

// checks if score of at least one student is less than 40  
if
(scoreObtained.some(studentIsPassed) == true)
 {
  console.log("At least one of the students failed.");
}

else
  console.log("All students are passed.");

Output

At least one of the students failed.

In the above example, we have used the some() method to find out if any of the students have scored marks less than 40.

We have passed callback in the method as scoreObtained.some(studentIsPassed) which returns

true

Since the test expression in the if statement is true, the program prints- At least one of the students failed.

Recommended Readings: JavaScript Array every()