How can you tell what type a value is, in JavaScript?
JavaScript has a few built-in types, including numbers, strings, booleans, objects.
Using the typeof
operator we can check what is the type of a value assigned to a variable.
For example:
typeof 'test'
Note that it’s not a function, it’s an operator, so parentheses are not required.
Using it, we will get a string back, returning one of the following values:
'number'
'string'
'boolean'
'undefined'
'bigint'
'symbol'
'object'
'function'
Note that there is no null
type, and
typeof null
will return 'object'
.
Arrays will return 'object'
too:
typeof [1, 2, 3] //'object'
Functions are a special kind of objects, as we can add properties and methods to functions:
const talk = () => {}
talk.test = true
but they have their own value 'function'
if we use the typeof
operator.
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