Sintaxis de JavaScript para check nulo o indefinido o vacío
if (typeof value !== 'undefined' && value) {
//deal with value'
};
Different Dugong
if (typeof value !== 'undefined' && value) {
//deal with value'
};var myVar=null;
if(myVar === null){
//I am null;
}
if (typeof myVar === 'undefined'){
//myVar is undefined
}