Getting to know the different data types in Javascript



October 12, 2020

Happy Monday guys 😁✌️

Today we have a pretty simple tip on the different data types in Javascript. It's always important to make sure we know the basics, right?

Basically there 8 data types: 7 primitive and 1 non-primitive. The only non-primitive type is 'object' and we use it for more complex data structures (objects, arrays, functions...)

We can check the type of a variable by using the 'typeof' operator. Check the example to see the different data types and how we can use this 'typeof' operator to get the data type for each const.

const isString = 'webDev Tips' console.log(typeof isString) // -> string const isNumber = 1231 console.log(typeof isNumber) // -> number const isBigInt = 43248204284204284294024324247924242n console.log(typeof isBigInt) // -> bigint const isBoolean = true console.log(typeof isBoolean) // -> boolean const isUndefined = undefined console.log(typeof isUndefined) // -> undefined const isNull = null console.log(typeof isNull) // -> object const isObj = { id: 2, name: 'John Doe' } console.log(typeof isObj) // -> object const isSymbol = Symbol('sym') console.log(typeof isSymbol) // -> symbol const isArray = ['banana', 'apple', 'peach'] console.log(typeof isArray) // -> object

Let's quickly go through each data type:

The string is used to represent textual data.
The number type is used to represent integers, floating-point numbers, +Infinity, -Infinity and NaN.
The bigint type is the most recent one here and it's used for large integers that the type number cannot represent.

The boolean type represents only one of two values: true or false.
The undefined type only represents the value 'undefined' when a variable has not been assigned a value.
The null type only holds the 'null' value and it represents 'nothing'. Due to a bug in Javascript, 'typeof null' returns 'object' instead of 'null'.

The object type, as said previously, is the only non-primitive data type and it's used to store collections of data.
The symbol type represents a unique identifier.

Finally, on the last example we have an array. As you can see, using the 'typeof' operator with an array also returns 'object'. This is right since array is not it's own data type.

And that's all! Let me know your thoughts 🤓🙏