typeOf
The typeof operator is used in either of the following ways:
- typeof operand
- typeof (operand)
The typeof operator will return a value relating to the type of object passed as the operand. A table is outlined below defining what this might be. If you click the test button you see the output of the Sample column beside it. In these cases I have used the parentheses but these are optional.
| Type | Result | Sample | Test |
|---|---|---|---|
| Undefined | "undefined" |
var undef; alert(typeof(undef)); |
|
| Null | "object" | alert(typeof(null)); | |
| Boolean | "boolean" | alert(typeof(true)); | |
| Number | "number" | alert(typeof(2)); | |
| String | "string" | alert(typeof('test')); | |
| Function object | "function" |
var myFun = new Function("test"); alert(typeof(myFunction)); |
|
| Any other object | "object" |
var myArr = new Array(); alert(typeof(myArr)); |
Some examples of functions
typeof Date == 'function' typeof Function == 'function' typeof Math == 'object' typeof Object == 'function' typeof String == 'function'
