Question

I’m fairly new to node.js, and don’t understand the assert module. What is the purpose of this? I’m trying to check if a certain value is equal to my defined value, however the app crashes (it says it will) when it’s false. What is the reason one would use assert? Is checking with a if statement the same thing or is this not proper?

Basically I’m using zombie.js to get the value of a input form.

assert.equal(browser.field('name').value, 'Mike'); 

vs

 if(browser.field('name').value == 'Mike'){
     //continue 
   }

Answer 1

Assertions are for testing and for surfacing bugs. Which are sort of the same thing.

Basically, the condition you put in an assert is something that you believe (as the programmer) absolutely positively must be true according to the logic you’ve programmed. Anything other than that should be impossible.

If an assertion triggers, it indicates that somehow something has happened to get things in a state that the programmer believes is impossible. Therefore, the right thing to do is to stop execution.

So assertions should generally never be used for normal program flow (including error checking). They should only be used for “whoa, hey, this should be impossible” things.

In your case, you definitely want an if and not an assertion, as the possibility that the statement might be false is absolutely something you expect to happen from time to time.

More info about assertions: http://en.wikipedia.org/wiki/Assertion_(computing)