Automatic type conversions by the addition operator (+)

Question | Nov 1, 2015 | nextptr 

JavaScript is a dynamic language and it does automatic data type conversions if required by operations.

Let's take all cases of data type conversions with the addition operator (+) into consideration.

Just like any other programming language '+' is used for adding numeric data or concatenating strings. In this case there are no automatic conversions:

console.log(40 + 2);   // 42
console.log("40" + "2");  // "402"

If one operand is a string the other operand is converted to string:

console.log("40" + 2); // "402"
console.log("40" + false);   // "40false"
console.log("40" + []);    // "40"

In cases where none of the two operands is a string and both operands are primitive (number, boolean, null, undefined), both operands are converted to numbers and added:

console.log(false + 3);     // 3
console.log(false + true);  // 1
console.log(null + true);   // 1
console.log(null + null);   // 0

If one operand is an object both operands are converted to strings and concatenated:

console.log([2] + 40);  // "240"

Also, keep in mind that '+' operator has left-to-right associativity. You can read more about operator associativity here.
Considering all the above cases of '+' operator, and answer which one of the followings will log 'true':

2015 nextptr