Question

I have the follwing jQuery:

        $("#textArea").keyup(function(){
            var textAreaValue = $("textArea");
            if(!textArea.value.indexOf("some string")){
                textArea.value = textArea.value.replace("some string",null);
                alert("It was there!");
            }
        });

• Is it normal for element.value.replace("some string",null); to replace "some string" with "null"as a string? And if normal can you please explain why?

• I have tested it with element.value.replace("some string",""), and that works fine, so what would be the difference between null and ""?

Using FireFox 3.6.3, Thanks in advance.

Answer 1

Seems like null has been type-casted to a String.

Try:

"a" + null // "anull"

Although you can’t call toString() on a null object, it seems the null object is implicitly being converted to a String, which gives the string "null".

String(null) // "null"