check if a value is null or undefined javascript code example

Example 1: javascript check for null variables

var myVar=null;

if(myVar === null){
    //I am null;
}

if (typeof myVar === 'undefined'){
    //myVar is undefined
}

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).
}