JavaScript Strings
Strings are for storing text
Strings are written with quotes
Using Quotes
A JavaScript string is zero or more characters written inside quotes.
You can use single or double quotes:
Example
let carName1 = "Volvo XC60";
// Double quotes
let carName2 = 'Volvo XC60'; // Single quotes
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Strings 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"';
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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:
String Length
To find the length of a string, use the built-in length property:
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
\" inserts a double quote in a string:
let text = "We are the so-called \"Vikings\" from the north.";
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\' inserts a single quote in a string:
let text= 'It\'s alright.';
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\\ inserts a backslash in a string:
let text = "The character \\ is called backslash.";
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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:
A safe way to break up a string is by using string addition:
Template Strings
Templates were introduced with ES6 (JavaScript 2016).
Templates are strings enclosed in backticks (`This is a template string`).
Templates allow multiline strings:
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");
Do not create String 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");
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When using the === operator, x and y are not equal:
let x = "John";
let y = new String("John");
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Note the difference between (x==y) and (x===y).
Comparing two JavaScript objects always returns false.
