Similar function being passed to find(0 but this time we have found the actual number. create the function to check if the item is oddįunction isOdd(i) //return the number this time > FIND INDEX OF A FRUIT WITH FINDINDEX()įirstly we will find the index of a fruit inside a fruit array using arrow functions:Ĭonst fruits = // find the index of the 'blueberries'Ĭonst index = fruits.findIndex(fruit => fruit = 'blueberries') Ĭonsole.log(fruits) // blueberriesĪs a use case this is good when we want to find the first item that matches our condition when it exists in the array. Otherwise, it returns -1, indicating no element passed the test.Īlso this is another example to find the odd element inside an array: I publish a few articles and tutorials each week, please consider entering your email here if you’d like to be added to my once-weekly email list.1.With findIndex() method we return the index of the first element in the array that satisfies the provided testing function. Therefor, if the remainder does not equal zero, we have an odd number: function isOdd(i) arr.findIndex(isOdd) // 4Īs expected, the index (4) of the odd number (9) is returned! Want more advanced JavaScript?Ĭheck out: A Beginners Guide to Advanced JavaScript An even number will always have a remainder of 0. To do this, we’ll check the remainder of the number divided by 2. Next, we need a function to determine if a number is odd. What if we have an Array with all even numbers and one odd number? We can find the odd number with Array.find(). If it does, the value of that entry is returned. In the above example we are testing each entry in the array to see if it equals ‘b’.

We’ll use an array with three entries: let arr = arr.find(k => k='b') // 'b' find() does not mutate or change the original Array.

If nothing passes, undefined is returned.

find() method executes a callback function once for each element in the array until it finds a value that returns true.

find vs findIndex (Array prototype methods) (version: 0). The Array.find() method returns the value of the first element in an array that passes a given test. JavaScript microbenchmarks, JavaScript performance playground.

Js findindex