The Seven Standard Primitives in JavaScript
Javascript has seven primitive data types:
- string
- number
- bigint
- boolean
- undefined
- symbol
- null
In JavaScript, a primitive is any value that isn't an object.
The typeof operator tells you what type a primitive value is.
String
It is important to note that strings can be either a primitive, string literal,
or an object. Javascript automatically converts string primitives to objects to enable
the user to use the handy array of functions available for use.
If you wanted to convert a string object to a primitive, you would
use the valueOf() method.
let message = "Hello World";
typeof message; // 'string'Number
In other programming languages, you can have numbers be defined as floats, integers,
doubles and so on and so forth. Javascript simplified this feature by just making
every number it comes across Number, with an exception.
let password = 123456789;
typeof password; // 'number'BigInt
This is similar to Number however, it allows you to safely represent integer values
larger than 253. You can create a bigint by appending n to the end of the
number or by wrapping the number, or string for this case, in the BigInt() constructor.
let launchCodes = 66777888889999912345n;
typeof launchCodes; // 'bigint'Boolean
This data type is what contains the values true or false. This is great in that
you can use other values to represent that same concept like 0 for false, and 1 for true.
isBool = true;
typeof isBool; // 'boolean'
// Instances of wrapper classes, like `Boolean`, are objects, **not** primitives.
typeof new Boolean(isBool); // 'object'Undefined
This value is automatically assigned to variables that have just been declared but not defined.
If you were to put this in an if statement, the value would be false so this is another handy thing
you could use like mentioned in the Boolean section.
let x;
typeof x; // 'undefined'Symbol
A Symbol is a value created by invoking the Symbol function
which is guaranteed to create a unique value. It takes one parameter, a string description, that
will show up when you print the symbol.
let x = Symbol("this is a symbol");
typeof x; // 'symbol'Null
null is special because the typeof operator reports its type as 'object'.
typeof null; // 'object'