Answers for "javascript check if variable undefined"

javascript check if not undefined

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

Javascript check if undefined

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

checking if var is not defined js

if(typeof x !== 'undefined'){
  alert("Variable x is defined.");
}

test if is undefined javascript

let id;

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

nodejs check if variable is undefined

if ( typeof query !== 'undefined' && query )
{
  //do stuff if query is defined and not null
}
else
{

}