I was in the middle doing some projects, an surprisingly i found something weird happen in javascript.
why :
-1 * 0 = -0 and 0 == -0 return true ? ( tested in chrome and firefox )
Anyone can explain ?
Any help really appreciated
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Do you really expect `-0 == 0` to return false? – p.s.w.g Mar 09 '17 at 04:12
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theoretically, yes. – Brian Alexandro Mar 09 '17 at 04:14
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they are both true.` -1 * 0` DOES equal `-0` so that is correct. `0` and `-0` are the same, the value of each is still `0`.... and you are comparing the value of them with `==` operator, so it is also correct :) – HolyMoly Mar 09 '17 at 04:14
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interesting. just checked that 0 === -0 return true too. so basically 0 and -0 is same value and same type – Erdo Dirgagautama Mar 09 '17 at 04:16
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Thanks for the reply. what about -1 * 0 = -0 ? isn't it should be 0 ? – Brian Alexandro Mar 09 '17 at 04:16
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also you are correct... `==` checks value, while `===` checks both value and type – HolyMoly Mar 09 '17 at 04:18
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"The rule for multiplying and dividing is very similar to the rule for adding and subtracting. When the signs are different the answer is negative. When the signs are the same the answer is positive." – HolyMoly Mar 09 '17 at 04:20
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Well, thanks for help guys. – Brian Alexandro Mar 09 '17 at 04:24
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1@ErdoDirgagautama The accepted answer on the linked question explains that `===` is explicitly designed to ignore the sign if the value is `0` or `-0`. – p.s.w.g Mar 09 '17 at 04:25