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You Don't Know JS: Types & Grammar - "What about &&" Code example not clear enough #948

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oriprice opened this issue Jan 17, 2017 · 3 comments · May be fixed by #1020
Open

You Don't Know JS: Types & Grammar - "What about &&" Code example not clear enough #948

oriprice opened this issue Jan 17, 2017 · 3 comments · May be fixed by #1020

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@oriprice
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@oriprice oriprice commented Jan 17, 2017

In What about &&? section we have the following code.

function foo() {
    console.log( a );
}

var a = 42;

a && foo(); // 42

result in comment should indicate that foo was called. but in fact we would get same result of "42" if first operand had been called (like in || operator). i think results of a and foo() should be different to make the example be clearer.

for example:

function foo() {
    console.log("foo");
}

var a = 42;

a && foo(); // "foo"
@ceckenrode

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@ceckenrode ceckenrode commented Apr 29, 2017

We're checking to see if a exists to see if we should call a function which depends on a. So this makes sense if you already understand short circuit evaluation to a degree, but the example does feel a little contrived.

It might be clearer if we were doing something with a instead of doing more than just console logging a on its own? Example:

function foo() {
    console.log(a * 2);
}

var a = 42;

a && foo(); // "84"

@oriprice

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@oriprice oriprice commented Apr 30, 2017

yes, anything different than the value of a (42) is better.

@getify

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@getify getify commented Aug 15, 2017

OK, fair point. We can tweak in second edition.

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