javascript test if undefined code example
Example 1: javascript check for undefined
if (typeof myVariable === 'undefined'){
//myVariable is undefined
}
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: js check if undefined
let foo = undefined
//will return true
typeof foo === 'undefined'
Example 4: javascript check undefined
if(myVar === null) {
console.log("Element is undefined");
}