How the answer is '#10' ?Pls explain the both ternary operator

Question

var a='#';
var b=null;
var c;
var a+=b==c? '1' : '0' ;
var a+=b===c? '1' : '0' ;
console.log(a);

Answer 1

Mohammad Tausiful Alam

null == undefined // true

So b == c //true

So a = a + 1 = #1

And b === c // false because null === undefined is false because type is not same

So a = a + '0' = #1 + '0' = #10

Answer 2

The ternary operator is basically a short form for a simple "if/else".
To rewrite the line:
If (b == c)
a += '1'
Else
a += '0'

Answer 3

Code produce errors.
Line 4,5 are has syntax errors. Check in playground... so it is not a clear question.

edit :

Mohammad Tausiful Alam

it may be
var a='#';
var b=null;
var c = a+=b==c? '1' : '0' ; //
a+=b===c? '1' : '0' ; //
console.log(a);

then :
var a='#';
var b = null;
var c = a+=b==c? '1' : '0' ; // it will be evaluated as
// a = a + ( b == c? '1' : '0' ) ; so b==c is
// null== undefined is true because both
// are 0 in int value so a = # + 1 =#1

a+=b===c? '1' : '0' ; // here this again b===c is
//false, same value but not same
//types so return false hence '0' is added to a => a = #10

console.log(a); // #10

Answer 4

Thanks to all. Got it