Answers for "how to check for undefined in js"

19

js if not undefined

if (typeof myVar !== "undefined") {
    console.log("myVar is DEFINED");
}
Posted by: Guest on October-23-2019
20

javascript check for undefined

if (typeof myVariable === 'undefined'){
    //myVariable is undefined
}
Posted by: Guest on July-22-2019
7

javascript if undefined

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

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

} else if(comment === null){

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

}
Posted by: Guest on March-25-2020
2

js check if undefined

let foo = undefined
//will return true
typeof foo === 'undefined'
Posted by: Guest on July-15-2020

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