Hands-On Data Structures and Algorithms with JavaScript

Truthy/falsy comparisons

We have all, at some point, written if conditions or assigned default values by relying on the truthy or falsy nature of the JavaScript variables. As helpful as it is most of the times, we will need to consider the impact that such an operation would cause on our application. However, before we jump into the details, let's discuss how any condition is evaluated in JavaScript, specifically an if condition in this case. As a developer, we tend to do the following:

if(objOrNumber) {    // do something}

This works for most of the cases, unless the number is 0, in which case it gets evaluated to false. That is a very common edge case, and most of us catch it anyway. However, what does the JavaScript engine have to do to evaluate ...