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javascriptarraysloops
abdulazeez
abdulazeez

Reputation: 71

How do I find the Index of the smallest number in an array in javascript

I have group of numbers. Without using methods, how to pick the index of the smallest number in JavaScript? Explain, how the code will work.

let numbers = [20, 90, 10, 324, 9, 73] //Example array of numbers.

Upvotes: 0

Views: 1340

Answers (2)

almarc
almarc

Reputation: 1658

Barebones, without methods:

let numbers = [20, 90, 10, 324, 9, 73]
let smallest = 0

for (i in numbers) {
  if (numbers[smallest] > numbers[i]) smallest = i
}

console.log(smallest)

First, we make a variable "smallest" and set it to 0, which is the first index of the array. Then, we go through the entire array and see if there's a number smaller than numbers[smallest], the initial value of which is 0. If there is, each time smallest is set to the index of that smaller number. By the end of the array, we have the variable smallest set to the index of the smallest number in the array. That's the solution without methods.

Using array methods and the Math library:

let numbers = [20, 90, 10, 324, 9, 73]
let smallest = numbers.indexOf(Math.min(...numbers))

console.log(smallest)

  • Math.min() takes a list of numbers and returns the smallest.
  • ...numbers is what's called "spreading". Math.min() takes parameters, not an array, (Math.min(1, 2, 3) not Math.min([1, 2, 3]). So ...numbers turns [20, 90, 10, 324, 9, 73] into (20, 90, 10, 324, 9, 73)
  • The .indexOf() method takes a value and finds the index of that value in an array.

Upvotes: 3

Zubair Idris Aweda
Zubair Idris Aweda

Reputation: 76

You can get the smallest number first

let numbers = [20, 90, 10, 324, 9, 73];
let smallest = Math.min(...numbers);

Then, you can get its index easily using the indexOf function.

let index = numbers.indexOf(smallest);

Upvotes: 0

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