js check variable is undefined 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: 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");
}