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JavaScript JavaScript Loops, Arrays and Objects Tracking Data Using Objects The Student Record Search Challenge Solution

Alec Sandoval
Alec Sandoval
1,687 Points
Posted by Alec Sandoval
Alec Sandoval
1,687 Points

or operator

I flipped flopped a certain line of code involving the "or":

if (search.toLowerCase() === 'quit' || search === null)

and got the error "student_report.js:20 Uncaught TypeError: Cannot read property 'toLowerCase' of null". Why is that line of code not the same as:

if (search === null || search.toLowerCase === 'quit')

2 Answers

Vladut Astalos
Vladut Astalos
11,246 Points
Vladut Astalos
Vladut Astalos
11,246 Points

Yes they mean the same thing but if the first condition is true, that means 'search' is null, then the second condition can not be verified because you can't apply toLowerCase() method on a null object.

Vladut Astalos
Vladut Astalos
11,246 Points
Vladut Astalos
Vladut Astalos
11,246 Points

I'm not sure but I think that happens because in your first example if the first condition is true then the second doesn't make sense anymore. I mean if search.toLowerCase() === 'quit', then is clearly that search isn't null, there is no need to check that. And in your second example if the first condition is true and search is indeed null than you can not convert it to lower case because there is nothing to convert.

Alec Sandoval
Alec Sandoval
1,687 Points
Alec Sandoval
Alec Sandoval
1,687 Points

Don't the two conditions mean the same thing? If (search === 'quit' OR search === null) vs if (search ===null OR search === 'quit')