javascript if string empty

1// Test whether strValue is empty or is None
2if (strValue) {
3    //do something
4}
5// Test wheter strValue is empty, but not None 
6if (strValue === "") {
7    //do something
8}

1// simple check do the job
2if (myString) {
3 // comes here either myString is not null,
4 // or myString is not undefined,
5 // or myString is not '' (empty).
6}

1var s; // undefined
2var s = ""; // ""
3s.length // 0
4