instanceof javascript code example

Example 1: js not instanceof

if ( !(obj instanceof Array) ) {
  console.log('obj is not an Array')
}

Example 2: instanceof javascript

var color = "red";
var color2 = {};
color instanceof String // will return true
color2 instanceof Object // will return true

Example 3: instance of

The instanceof keyword checks whether an object
is an instance of a specific class or an interface.
The instanceof keyword compares the
instance with type. The return value
is either true or false .

Example 4: javascript check if variable is object

//checks if is object, null val returns false
function isObject(val) {
    if (val === null) { return false;}
    return ( (typeof val === 'function') || (typeof val === 'object') );
}
var person = {"name":"Boby Snark"};
isObject(person);//true

Example 5: js class check if new instance

new Date() instanceof Date;  // => true

Example 6: insanceof

The instanceof operator tests to see if the prototype property of a constructor 
appears anywhere in the prototype chain of an object. The return value is a 
boolean value.
For example :-

function Car(make, model, year) {
  this.make = make;
  this.model = model;
  this.year = year;
}
const auto = new Car('Honda', 'Accord', 1998);

console.log(auto instanceof Car);
// expected output: true

console.log(auto instanceof Object);
// expected output: true