check undefined in node js code example

Example 1: js if not undefined

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

Example 2: how to check if object is undefined in javascript

if (typeof something === "undefined") {
    alert("something is undefined");
}

Example 3: nodejs check if variable is undefined

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

}

Example 4: undefined javascript check

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

Example 5: How can I check whether a variable is defined in Node Js

if (query){
   doStuff();
}