The instanceof operator determines whether a left-hand side object is created from a specified constructor function in its prototype chain.
object instanceof constructor
- object = variable name
- constructor = constructor function name used with the "new" keyword
function func1(){ };
function func2(){ };
var f1 = new func1();
f1 instanceof func1; //returns true
f1 instanceof func1; //returns false
f1 instanceof Object; //returns true
Please note that the instanceof operator returns "true" if a variable is initialized with the "new" keyword.
var stringObj = new String();
var str = "this is str";
stringObj instanceof String; //returns true
str instanceof String; //returns false
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