Use typeof
:
> typeof "foo"
"string"
> typeof true
"boolean"
> typeof 42
"number"
So you can do:
if(typeof bar === 'number') {
//whatever
}
Be careful though if you define these primitives with their object wrappers (which you should never do, use literals where ever possible):
> typeof new Boolean(false)
"object"
> typeof new String("foo")
"object"
> typeof new Number(42)
"object"
The type of an array is still object
. Here you really need the instanceof
operator.
Update:
Another interesting way is to examine the output of Object.prototype.toString
:
> Object.prototype.toString.call([1,2,3])
"[object Array]"
> Object.prototype.toString.call("foo bar")
"[object String]"
> Object.prototype.toString.call(45)
"[object Number]"
> Object.prototype.toString.call(false)
"[object Boolean]"
> Object.prototype.toString.call(new String("foo bar"))
"[object String]"
> Object.prototype.toString.call(null)
"[object Null]"
> Object.prototype.toString.call(/123/)
"[object RegExp]"
> Object.prototype.toString.call(undefined)
"[object Undefined]"
With that you would not have to distinguish between primitive values and objects.
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