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javascriptjslint

Implicit cast/number check produces 'unexpected X' JSLint error

this is nothing serious, but just a question out of curiosity. The following script in JSLINT.com gives a strange and 'unexpected' error. My script works, but I would still like to know if anyone can explain the error. 

var hashVar = parseInt(location.hash.replace('#',''), 10);
if(hashVar-0 === hashVar){L();}

ERROR: Problem at line 3 character 4: Unexpected 'hashVar'.

Enjoy the weekend, Ulrik

Solution

  • You probably want this: 

    var hashVar = parseInt(location.hash.replace('#', ''), 10);
if ( !isNaN(hashVar) ) { L(); }

    This code has the same functionality as your original code.

    BTW, this:

    if ( !isNaN(hashVar) ) { L(); }

    can be further reduced to this:

    isNaN(hashVar) || L();

    ;-)

    Explanation:

    The return value of parseInt can be:

    a) an integer numeric value
    b) the NaN value

    Therefore, if you want to test whether the return value is an integer or not, just use isNaN().