javascript - Jslint use '||' operator instead of conditional operator

I have jslint plaining me to use || operator for below code,

query = ['browser' + (ieVersion ? ieVersion : 'UNKNOWN')]

I tried using || operator but that ends up in wrong result,

query = ['browser' + ieVersion || 'UNKNOWN'] 
// => ['browserundefined']

I have jslint plaining me to use || operator for below code,

query = ['browser' + (ieVersion ? ieVersion : 'UNKNOWN')]

I tried using || operator but that ends up in wrong result,

query = ['browser' + ieVersion || 'UNKNOWN'] 
// => ['browserundefined']

Share Improve this question edited Dec 18, 2012 at 18:01 asked Dec 18, 2012 at 17:36 Mahesh Kulkarni 3073 silver badges11 bronze badges

Sorry my bad, I did try with parentheses. Will update the question now – Mahesh Kulkarni Commented Dec 18, 2012 at 17:55
Um. But it works with parens, as in the answer you accepted. – Dave Newton Commented Dec 18, 2012 at 18:01
Edit: I screwed. I actually din't use brackets. I will always worry about precedence from now on. – Mahesh Kulkarni Commented Dec 18, 2012 at 18:01

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3 Answers 3

Sorted by: Reset to default 6

Operator precedence is wrong, try this:

query = ['browser' + (ieVersion || 'UNKNOWN')]

without extra parentheses + operator is stronger and JavaScript engine evaluates it as:

query = [('browser' + ieVersion) || 'UNKNOWN']

Notice that 'browser' + ieVersion is never falsy so you'll never see 'UNKNOWN'.

brackets?

query = ['browser' + (ieVersion || 'UNKNOWN')]

You need to wrap the expression in parentheses:

query = ['browser' + (ieVersion || 'UNKNOWN')]