detect undefined variable javascript code example
Example 1: js if not undefined
if (typeof myVar !== "undefined") {
console.log("myVar is DEFINED");
}
Example 2: checking if var is not defined js
if(typeof x !== 'undefined'){
alert("Variable x is defined.");
}
Example 3: undefined javascript check
if(undefinedElement === null) {
console.log("Element is undefined");
}