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