JavaScript string

A string is a sequence of one or more characters that may consist of letters, numbers, or symbols. Strings in JavaScript are primitive data types and immutable, which means they are unchanging.

JavaScript strings are for storing and manipulating text.

  A JavaScript string is zero or more characters written inside quotes.

let text = "John Doe";        

use single or double quotes

• The following example is the use of string both method single or double quotes

let carName1 = "Volvo XC60";  // Double quotes
let carName2 = 'Volvo XC60';  // Single quotes       

quotes inside a string

  You can use quotes inside a string, as long as they don't match the quotes surrounding the string:

<script>  
let answer1 = "It's alright";
let answer2 = "He is called 'Johnny'";
let answer3 = 'He is called "Johnny"';
</script>             

String Length

  To find the length of a string, use the built-in length property:

let text = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
let length = text.length;         

Escape Character

  Because strings must be written within quotes, JavaScript will misunderstand this string:

let text = "We are the so-called "Vikings" from the north.";      

  The string will be chopped to "We are the so-called ".

  The solution to avoid this problem, is to use the backslash escape character.

  The backslash (\) escape character turns special characters into string characters:

  The sequence \" inserts a double quote in a string:

let text = "We are the so-called \"Vikings\" from the north.";     

  The sequence \\ inserts a backslash in a string:

let text = "The character \\ is called backslash.";  

  Six other escape sequences are valid in JavaScript:

Breaking Long Code Lines

  For best readability, programmers often like to avoid code lines longer than 80 characters.

document.getElementById("demo").innerHTML =
"Hello Dolly!";    

  You can also break up a code line within a text string with a single backslash:

document.getElementById("demo").innerHTML = "Hello \
Dolly!";   

JavaScript Strings as Objects

  Normally, JavaScript strings are primitive values, created from literals:

let x = "John";    

  But strings can also be defined as objects with the keyword new:

let y = new String("John"); 

let x = "John";
let y = new String("John");

Do not create Strings objects.

The new keyword complicates the code and slows down execution speed.

String objects can produce unexpected results:

  When using the == operator, x and y are equal:

let x = "John";
let y = new String("John");