Flash cards
Review the key moves
What is the main idea behind JavaScript Strings?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
___ text = "John Doe";Put the learning moves in the order that makes the concept easiest to apply.
Strings are for storing text
Strings are written with quotes
Using Quotes
A JavaScript string is zero or more characters written inside quotes.
Example
let text = "John Doe";You can use single or double quotes:
Example
let carName1 = "Volvo XC60";
// Double quotes
let carName2 = 'Volvo XC60'; // Single quotesStrings created with single or double quotes work the same.
There is no difference between the two.
Quotes Inside Quotes
You can use quotes inside a string, as long as they don't match the quotes surrounding the string:
Example
let answer1 = "It's alright"; let answer2 = "He is called 'Johnny'"; let answer3 = 'He is called "Johnny"';Template Strings
Templates were introduced with ES6 (JavaScript 2016).
Templates are strings enclosed in backticks (This is a template string).
Templates allow single and double quotes inside a string:
Example
let text = `He's often called "Johnny"`;String Length
To find the length of a string, use the built-in length property:
Example
let text = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
let length = text.length;Escape Characters
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 ".
To solve this problem, you can use an backslash escape character .
The backslash escape character ( \ ) turns special characters into string characters:
| Code | Result | Description |
|---|---|---|
| \' | ' | Single quote |
| \" | " | Double quote |
| \\ | \ | Backslash |
Examples
let text = "We are the so-called \"Vikings\" from the north.";Six other escape sequences are valid in JavaScript:
| Code | Result |
|---|---|
| \b | Backspace |
| \f | Form Feed |
| \n | New Line |
| \r | Carriage Return |
| \t | Horizontal Tabulator |
| \v | Vertical Tabulator |
The 6 escape characters above were originally designed to control typewriters, teletypes, and fax machines. They do not make any sense in HTML.
Breaking Long Lines
For readability, programmers often like to avoid long code lines.
A safe way to break up a statement is after an operator:
Example
document.getElementById("demo").innerHTML = "Hello Dolly!";A safe way to break up a string is by using string addition:
Example
document.getElementById("demo").innerHTML = "Hello " + "Dolly!";Template Strings
Templates were introduced with ES6 (JavaScript 2016).
Templates are strings enclosed in backticks (This is a template string).
Example
let text = `The quick
brown fox
jumps over
the lazy dog`;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");Example
let x = "John";
let y = new String("John");Do not create String objects.
The new keyword complicates the code and slows down execution speed.
String objects can produce unexpected results
=====Note the difference between (x==y) and (x===y) .
(x == y)(x === y)Comparing two JavaScript objects always returns false .
Learn More
JavaScript String Methods
JavaScript String Search
JavaScript String Reference