javascript null vs undefined code example

Example 1: null undefined javascript

Undefined  used for unintentionally missing values.

Null       used for intentionally missing values.

Example 2: javascript check for null variables

var myVar=null;

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

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

Example 3: js null vs undefine

var TestVar = null;
alert(TestVar); //shows null
alert(typeof TestVar); //shows object

Example 4: js null vs undefine

var TestVar;
alert(TestVar); //shows undefined
alert(typeof TestVar); //shows undefined