typeof undefined javascript code example

Example 1: javascript typeof undfined

var x;
if (typeof x === 'undefined') {
   // these statements execute
}

Example 2: how to check if object is undefined in javascript

if (typeof something === "undefined") {
    alert("something is undefined");
}

Example 3: javascript check if boolean is undefined

if (typeof myFlag !== "undefined") {
  // comes here whether myFlag is true or false but not defined
}

Example 4: javascript type of undefined

if (typeof x == 'undefined'){
   // instructions
 }