undefined javascript check

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

3.9
10
Avi Singh 75 points

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

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

} else if(comment === null){

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

}

3.9 (10 Votes)
0
3.5
2

                                    let foo = undefined
//will return true
typeof foo === 'undefined'

3.5 (2 Votes)
0
0
0
Dreamlike 80 points

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

0
0
4.75
4

                                    let id;

if(typeof id === 'undefined') {
    console.log("id is undefined...");
}

4.75 (4 Votes)
0
4
3

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

4 (3 Votes)
0
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