This is a simple javascript syntax issue

Question

I want to know if these two things are the same. In my brain they are. I am overall just trying to understand the javascript syntax better. In my brain these are the same. Please let me know why I am crazy! Thanks,

is this first one

if (edited === 'true' || edited === '')

the same as this?

if (edited == 'true' && '')

No they are not. In one condition, you are using || and second && — Ani
– Ani, Commented Jan 10, 2014 at 21:07
The first one has a possibility of being true. The second one doesn't! — johnnycardy
– johnnycardy, Commented Jan 10, 2014 at 21:08
Think if (expression && expression). Where each expression evaluates to either true or false and && evaluates the second expression if the first one is true. — elclanrs
– elclanrs, Commented Jan 10, 2014 at 21:11
Please read about Logical Operators and Comparison Operators at MDN. — Teemu
– Teemu, Commented Jan 10, 2014 at 21:45
@user3174713 - Please choose an accepted answer by using the green checkbox next to the answer that helped the most. This will allow future coders a reference to the issue. — Nicholas Hazel
– Nicholas Hazel, Commented Jan 16, 2014 at 2:14

gen_Eric · Accepted Answer · 2014-01-10 21:08:06Z

6

No. They are completely different.

In the first one, it checks to see if either edited === 'true' or edited === '' is true.

In the second one, it checks to see if both edited == 'true' and '' are true. '' converts to false, so the second one is like doing edited == 'true' && false or just simply false.

answered Jan 10, 2014 at 21:08

gen_Eric

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Nicholas Hazel · Accepted Answer · 2014-01-17 06:34:35Z

4

These are called logical operators.

Here is what each one does:

&& - Tests if BOTH conditions are true

|| - Tests if EITHER conditions are true

For your code:

if (edited === 'true' || edited === '') you could actually do...

if (edited === 'true || '') Tests if edited === true OR false and if either is true, run it.

if (edited === 'true' && '') Tests if edited === true AND false

Clearly the last one will never work, as edited is considered the same as false, null, 0, etc.

edited Jan 17, 2014 at 6:34

answered Jan 10, 2014 at 21:13

Nicholas Hazel

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Nicholas Hazel Over a year ago

@user3174713 - Please choose an accepted answer by using the green checkbox next to the answer that helped the most. This will allow future coders a reference to the issue.

user1329482 · Accepted Answer · 2014-01-10 21:08:10Z

1

No. Empty quotes always returns a "falsy" value, so your second test will either return true && false, or false && false.

answered Jan 10, 2014 at 21:08

user1329482

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riotgear Over a year ago

I get it now. I have a long ways to go it seems!

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