JavaScript Interview Question #18: What's the sum of two booleans in JavaScript?

coderslang

Coderslang: Become a Software Engineer

Posted on February 22, 2021

JavaScript Interview Question #18: What's the sum of two booleans in JavaScript?

js-test-18

Can you add booleans in JS? Is something false here? What will be logged to the screen?

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Just as in the previous test, we’re dealing here with type conversion and loose equality using the == operator.

When JavaScript evaluates the expression true + true it first converts booleans to numbers, which is 1 for true and 0 for false.

When we try to do calculate the value of 2 == true, the typecast happens again and we arrive at the final condition 2 == 1.

The result is obviously false, so we go into the else branch.

To understand how type conversion works with the + operator and different data types, you can read this article.


ANSWER: the string everyone is different after all will be logged to the console.

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coderslang
Coderslang: Become a Software Engineer

Posted on February 22, 2021

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