setTimeout() and setTimeInterval() are not part of the JavaScript language itself. They are browser APIs that sit on top of the JavaScript language.

setTimeout()

Executes a specified block of code once after a set period of time.

setTimeout takes the following parameters:

• A function to run or a reference to a function defined elsewhere.

• A number representing the time (in milliseconds) to wait before executing the code. If you specify a value of 0, the function runs as soon as possible.

Note: The callback is run as soon as possible, not immediately, because it has to wait for the stack on the main thread to be empty before it can run.

• Zero or more values that represent any parameters you want to pass to the function when it is run.

Examples:

Using an anonymous function;

// Anonymous function
setTimeout(function () {
  console.log(`Hello World!`)
}, 2000)

Using a named function:

setTimeout(function greeting() {
  console.log(`Hello World!`)
}, 2000)

Below, we pass a reference to the greeting() function as the first argument of setTimeout.

function greeting() {
  console.log(`Hello World!`)
}

setTimeout(greeting, 2000)

Passing parameters to the function:

function greeting(name) {
  console.log(`Hello ${name}`)
}

setTimeout(greeting, 2000, "hemanta")

setInterval()

Executes a specified block of code at regular interval.

setInterval() works in a very similar way to setTimeout( ) except the function you pass as the first parameter is executed repeatedly at the time interval specified by the second parameter.

Example:

function greeting(name) {
  console.log(`Hello ${name}`)
}

setInterval(greeting, 2000, "hemanta")