of([]string) is undefined in set code example

Example 1: javascript check if object is null or empty

if (typeof value !== 'undefined' && value) {
    //deal with value'
};

Example 2: javascript check if undefined or null or empty string

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