Answers for "javascript checking for undefined"

javascript check for undefined

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

javascript if undefined

if(typeof comment === 'undefined') {

  alert('Variable "comment" is undefined.');

} else if(comment === null){

  alert('Variable "comment" is null.');

}

undefined javascript check

if(undefinedElement === null) {
	console.log("Element is undefined");
}