find-index-x

find-index-x

This method returns the index of the first element in the array that satisfies the provided testing function.

module.exports ⇒ number ⏏

Like findIndex, this method returns an index in the array, if an element in the array satisfies the provided testing function. Otherwise -1 is returned.

Kind: Exported member
Returns: number - Returns index of positively tested element, otherwise -1.
Throws:

• TypeError If array is null or undefined-
• TypeError If callback is not a function.

Example

import findIndex from 'find-index-x';
 
function isPrime(element, index, array) {
  let start = 2;
  while (start <= Math.sqrt(element)) {
    if (element % start < 1) {
      return false;
    }
 
    start += 1;
  }
 
  return element > 1;
}
 
console.log(findIndex([4, 6, 8, 12, 14], isPrime)); // -1, not found
console.log(findIndex([4, 6, 7, 12, 13], isPrime)); // 2