CODEWITHSUNDEEP
javascriptsyntax
theking963
theking963

Reputation: 2226

Javascript Return Syntax

I am editing someone's code and I don't understand what they are trying to do with this statement. This is at the end of the function.

 return !(this.variable == "value")

Upvotes: 0

Views: 466

Answers (4)

Tony
Tony

Reputation: 2754

It's returning a true or false...

the exclamation point is a NOT...

so this.variable not equal to "value".

Upvotes: 0

domvoyt
domvoyt

Reputation: 416

They are checking this.variable is equal to "value" (which returns either true or false) and then using the ! (not) to make the value opposite.

It achieves the same result as

return (this.variable != "value")

You might as well change it to that because it is much clearer.

Upvotes: 0

bmm6o
bmm6o

Reputation: 6505

this.variable == "value"

This compares two values and evaluates to a boolean (true if they compare equal).

!(this.variable == "value")

This negates the value (true <-> false).

return !(this.variable == "value")

This returns the value from the function.

Upvotes: 0

Pointy
Pointy

Reputation: 413720

They're returning true or false based on the opposite of the result of the comparison.

It would probably have been clearer to write:

return this.variable != "value";

Sometimes you see:

return !!(some.expression);

which forces a "truthiness" conversion of the result of the expression to boolean (true or false). The "!!" is just a pair of individual logical complement ("not") operators. The first one (on the right) converts the result of the expression to boolean, but the opposite of the "truthiness". The second therefore flips it back.

Upvotes: 6

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