how to check falsy with undefined or null?

Question

undefined and null are falsy in javascript but,

var n = null;
if(n===false){
console.log('null');
} else{
console.log('has value');
}

but it returns 'has value' when tried in console, why not 'null' ?

Answer 1

To solve your problem:

You can use not operator(!):

var n = null;
if(!n){ //if n is undefined, null or false
console.log('null');
} else{
console.log('has value');
}
// logs null

To answer your question:

It is considered falsy or truthy for Boolean. So if you use like this:

var n = Boolean(null);
if(n===false){
console.log('null');
} else{
console.log('has value');
}
//you'll be logged null

Answer 2

You can check for falsy values using

var n = null;
if (!n) {
    console.log('null');
} else {
    console.log('has value');
}

Demo: Fiddle

---

Or check for truthiness like

var n = null;
if (n) { //true if n is truthy
    console.log('has value');
} else {
    console.log('null');
}

Demo: Fiddle