Question

What is the difference between…

if(myVar.constructor == String)

and

if(typeof myVar == "string")

Answer 1

The expression myVar.constructor just returns the value of the member “constructor”. It’s completely possible and legal for a given object to have a constructor which points to string (or anything else). For example

function Apple() {}
var x = new Apple();
x.constructor = String
if (x.constructor == String) {
  // True
}

Using the typeof operator though provides the information you’re looking for

if (typeof myVar == 'string') {
  // It's a string
}