angular check string is null or empty code example

Example 1: javascript is not null

if(data !== null && data !== '') {
   // do something
}

Example 2: javascript if string empty

// Test whether strValue is empty or is None
if (strValue) {
    //do something
}
// Test wheter strValue is empty, but not None 
if (strValue === "") {
    //do something
}