Is it safe (and better) to multiply with boolean?

Question

I have a piece of code that has a lot of if and else if. And I just thought now that in multiplication, true evaluates to 1 and false evaluates to 0. Would it be safe and easier to read (because it's shorter) to substitute :

if(!this._isFetched('studentInfoFetched')) { 
        tempAddedTime += 1;
        estimatedTimePerStudent += 0.04 + 0.2;
}
if(formInputValues.student_expiration){
        tempAddedTime += (!this._isFetched('studentExpirationFetched'))? 14 : 0;
        estimatedTimePerStudent += 1; 
}  

for :

    tempAddedTime += 1 * (!this._isFetched('studentInfoFetched')) + 14 * (!this._isFetched('studentExpirationFetched')) * (formInputValues.student_expiration);
    estimatedTimePerStudent += 0.24 * (!this._isFetched('studentInfoFetched')) + 1 * (formInputValues.student_expiration);

Note :_isFetched returns a bool. And this is just an example, for other cases I have a lot more if's so it would be saving me more lines.

Answer 1

No, the ifs - version is better.

Reasons:

• It's much more readable: expressions are shorter, and the lines are not too long. For example, I see a horizontal scrollbar on my screen for your multiplication expressions, while I don't have to scroll in the if-snippet :)

• It's faster because you avoid the multiplication.

• It's even faster because you avoid calling this._isFetched('studentInfoFetched') twice.

• ifs semantically define program flow, while the multiplication is semantically a mathematical expression which is used to fake the program flow in this case. With ifs, statements are grouped by condition, and you see at a glance what happens if a certain condition is met.

Then, consider that you have to create two more if clauses. The multiplication would become totally unmaintainable.

Answer 2

The code should be easy to read, quick to understand, and fast to change.

Better than comments that go out off time is clear variable names, although they're good for a general desctiption of why. Name constant (ie. what is 0.04 + 0.2??), and name expressions for brevity in context (also avoids unnecessary function calls).

// Estimate process time
const infoFetched = this._isFetched('studentInfoFetched')
const infoFetchTime = 0.04 + 0.2
const canExpire = formInputValues.student_expiration
const expirationFetched = this._isFetched('studentExpirationFetched')
const expirationFetchTime = 14

if (!infoFetched) tempAddedTime += 1
if (hasExpired && !expirationFetched) tempAddedTime += expirationFetchTime

if (!infoFetched) estimatedTimePerStudent += fetchTime
if (hasExpired) estimatedTimePerStudent += 1

I usually like to multiply booleans as toggles, although in this case, the if's might be a little bit easier to read, understand, and change;

tempAddedTime +=
    !infoFetched* 1 +
    (hasExpired && !expirationFetched)* expirationFetchTime

estimatedTimePerStudent +=
    !infoFetched* fetchTime +
    hasExpired* 1

Not the best example, would probably be quite different if I had access/knowledge about what it itended to do / the source