The following example shows in an alert dialog the length of the string "this is a test":
var mystring = "this is a test"; alert( mystring.length );
And here's the above as a working example:
It's also possible to do this -> "this is a test".length <- which is what the example button above is doing in the onclick event handler.
Apologies to my regular readers for such a basic post, but sometimes I need to write these simple posts so I will always remember a particular function in the future.