js if not undefined code example

Example 1: js if not undefined

if (typeof myVar !== "undefined") {
    console.log("myVar is DEFINED");
}

Example 2: javascript if undefined

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

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

} else if(comment === null){

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

}

Example 3: if not undefined javascript

if(typeof myVar !== "undefined")

Example 4: undefined javascript check

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