Answers for "javascript how to check undefined"

javascript check if not undefined

if (typeof myVar !== "undefined") {
    console.log("myVar is DEFINED");
}

javascript check for undefined

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

test if is undefined javascript

let id;

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

js check if undefined

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

javascript test if undefined

if (angular.isDefined(var){
    //myVariable is undefined
}

undefined javascript check

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