JavaScript Strings
A JavaScript string simply stores a series of characters like "John Doe".
A string can be any text inside quotes. You can use single or double quotes:
You can use quotes inside a string, as long as they don't match the quotes surrounding the string:
Example
var answer = "It's alright";
var answer = "He is called 'Johnny'";
var answer = 'He is called "Johnny"';
Try it Yourself
String Length
The length of a string is found in the built in property length:
Special Characters
Because strings must be written within quotes, JavaScript will misunderstand this string:
var y = "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 \ escape character.
The backslash escape character turns special characters into string characters:
Example
var x = 'It\'s alright';
var y = "We are the so-called \"Vikings\" from the north."
Try it Yourself
The escape character (\) can also be used to insert other special characters in a string.
This is the list of special characters that can be added to a text string with the backslash sign:
| Code | Outputs |
|---|---|
| \' | single quote |
| \" | double quote |
| \\ | backslash |
| \n | new line |
| \r | carriage return |
| \t | tab |
| \b | backspace |
| \f | form feed |
Breaking Long Code Lines
For best readability, programmers often like to avoid code lines longer than 80 characters.
If a JavaScript statement does not fit on one line, the best place to break it is after an operator:
You can also break up a code line within a text string with a single backslash:
The \ method is not a ECMAScript (JavaScript) standard. Some browsers do not allow spaces behind the \ character.
The safest (but a little slower) way to break a long string is to use string addition:
You cannot break up a code line with a backslash:
Strings Can be Objects
Normally, JavaScript strings are primitive values, created from literals: var firstName = "John"
But strings can also be defined as objects with the keyword new: var firstName = new String("John")
Example
var x = "John";
var y = new String("John");
// typeof x will return string
// typeof y will return object
Try it Yourself
Don't create strings as objects. It slows down execution speed. The new keyword complicates the code. This can produce some unexpected results:
When using the == equality operator, equal strings looks equal:
Example
var x = "John";
var y = new String("John");
// (x == y) is true because x and y have equal values
Try it Yourself
When using the === equality operator, equal strings are not equal, because the === operator expects equality in both type and value.
Example
var x = "John";
var y = new String("John");
// (x === y) is false because x and y have different types
(string and object)
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Or even worse. Objects cannot be compared:
Example
var x = new String("John");
var y = new String("John");
// (x == y) is false because x and y are different objects
// (x == x) is
true because both are the same object
Try it Yourself
JavaScript objects cannot be compared.