Shoutbox

Is there an easy way to convert a boolean value to a numeric value?

The boolean values are either true or false, and I want it to return either 1 or 0, respectively.

Im using an if statement right now, but Im wondering if there is a simpler way?

Like this:
var b = true;
var x= b?1:0;

ok, thanks. Im now using

code:

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myVar = myVar?1:0;

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A little bit shorter than my 5 lines I was previously using

code:

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var myNumber = parseInt(myBoolean);

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You could always multiply it by 1 or something as well.

I believe Math.abs(<boolean>) also does that.

quote:

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Originally posted by phalanxii
I believe Math.abs(<boolean>) also does that.

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This will give the absolute value of the number which is not what you want.  Boolean expressions are equivalent to 1 for true, 0 for null and -1 for false and thus you would have a problem where you couldn't tell the difference between true and false.  Even Spunky's code is incorrect because it misses the null possibility and false should be negate one not zero.  The proper methods would be either to use the parseInt method or multiply the boolean variable by 1 (or minus zero).  This is also the same when you try to convert a string to a number.

As a matter of fact, null is not a Boolean data type, but its own special 'null' data type.

According to MSDN:

quote:

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Whereas the string and number data types can have a virtually unlimited number of different values, the Boolean data type can only have two. They are the literals true and false.

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And in ordinary computing, true is 1 and false is 0, which is exactly what Math.abs() and Spunky's code return for those respective values.

Also, the parseInt() method will return NaN if you pass a Boolean into it. However, multiplying a Boolean by 1 works.

If the only reason you are doing this is to pass to a WinAPI or DLL function, just pass the boolean and it will be converted automatically by Plus. Otherwise, just use parseInt, multiply by one, or an inline if statement (b?1:0).

parseInt does not work for Booleans. It only works for strings. Passing a Boolean into it will result in NaN (not a number). Just do a simple debug trace and you will see.

Personally I would use an inline if statement, as the other methods could potentially give you a -1 as your number.

You could even make it a function of the boolean object (but this is sort of overkill):

code:

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Boolean.prototype.toInt = function () { return this ? 1 : 0; }

// to use it, just call the toInt member of a boolean object
function doSomethingWithBooleans() {
var bMyBoolean = true;
var nBoolAsInteger = bMyBoolean.toInt();
}

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