While working with my last project I observed that at every place when I need to validate Javascript variable I need to check two or more conditions. So I write one function which will check whether particular object or variable is valid or not for you. I hope this will helpful to you.
function isValid(obj)
{
if(typeof obj === "undefined" || obj === null || obj === "" || obj === "null" || obj === "{}"){
return false;
}
return true;
}