Method Chaining

Method chaining means calling one method after another in a single expression.

It is useful when each method returns a value that the next method can use.

Without Method Chaining

let username = window.prompt("Enter your username")
 
username = username.trim()
let firstLetter = username.charAt(0)
firstLetter = firstLetter.toUpperCase()
 
let extraChars = username.slice(1)
extraChars = extraChars.toLowerCase()
 
username = firstLetter + extraChars
console.log(username)

With Method Chaining

let username = window.prompt("Enter your username")
 
username =
  username.trim().charAt(0).toUpperCase() +
  username.trim().slice(1).toLowerCase()
 
console.log(username)