What are the possible side-effects in javascript?

A side effect is the modification of the state through the invocation of a function or expression. These side effects make our function impure by default. Below are some side effects which make function impure,

- Making an HTTP request. Asynchronous functions such as fetch and promise are impure.

- DOM manipulations

- Mutating the input data

- Printing to a screen or console: For example, console.log() and alert()

- Fetching the current time

- Math.random() calls: Modifies the internal state of Math object