# Asymptotic Notation: JavaScript

Learn about the asymptotic notation of JavaScript data structures and functions.

## Analyzing Runtimes

Now that you’ve started learning how to use asymptotic notation to measure the runtime of a function, let’s practice with JavaScript!

When analyzing the runtime of a function, it’s necessary to check the number of iterations the loop will perform based on the size of the input.

The `divideByTwo()`

function below takes in a positive integer of size `n`

, and returns the number of times `n`

must be divided by `2`

until it reaches `1`

.

We can analyze the runtime of this function by counting the number of iterations the `while`

loop will perform based on the size of the input (`n`

).