how to check variable has value or not in javascript code example

Example 1: javascript is not null

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

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).
}