Strings in JavaScript

Important points to note about Strings are given below

  1. Strings are primitive data types
  2. Strings are passed by value
  3. All strings inherit methods defined in String.prototype
  4. Strings are immutable in JavaScript
  5. Literal Strings do not have any methods of its own
  6. Literal Strings inherit methods from String.prototype using Autoboxing process

String methods in JavaScript

//string methods

let name = "Harry Potter"

//get the length of string
console.log(name.length)
//output - 12

//replace the specific portion of string
console.log(name.replace("Harry","Tom"))
//output - Tom Potter

//replace the specific portion of string using regular expression
console.log(name.replace(/h.*y/i,"Tom"))
//output - Tom Potter

//remove all blank spaces from the string using regular expression
console.log("Remove space " + name.replace(/\s/i,""))
//output - HarryPotter

//split the string
console.log(name.split(" ")[0])
//output - Harry

//search the substring
console.log(name.search(/arry/))
//output - 1

//search the substring using indexOf - 
//This method can not take regular expression
console.log(name.indexOf("arry"))
//output - 1

//extract substring starting from index
console.log(name.slice(6))
//output - Potter

//trim
console.log(name.trim())
//output - Harry Potter

//change case
console.log(name.toLowerCase())
//output - harry potter

Numbers in JavaScript

//Number methods

console.log(12 + 13)
//output - 25

console.log(12 + "13")
//output - 1213

console.log(12 + 0.3)
//output - 12.3

let x = 2.34344545;
console.log(x.toFixed(2))
//output - 2.34

console.log(x/"sd")
//output - NaN

console.log(x/0)
//output - Infinity


console.log(parseInt("234 fdf"))
//output - 234

console.log(parseInt(" fdf"))
//output - NaN

console.log(parseFloat("234.43 fdf"))
//output - 234.43

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