Wish to check if a style exists; create it if it doesn't exist.

Hello,

I am trying to write a script that will check to see if a style already exists in a document. If it does, fine, I'll use it. If it does not, then I want to create the style. The following script errors out, telling me there is an invalid parameter.

if(document.objectStyles.item().name !== myCharStyle){
var myCharStyle = myDoc.characterStyles.add({name:"myCharStyle"});
}

I have tried using the try/catch function as it is written in Adobe's InDesign Scripting Guide: JavaScript but this also just errors out.

Thanks,
Tom