Is this correct?

[javierdlm001]

According to page 26 in this PDF tutorial from Tutorials Point, it says the result would be "true", but is actually giving "false".
It goes like this:

Assume variable A holds 10 and variable B holds 20, then:

1. && (Logical AND)
If both the operands are non-zero, then the condition becomes true.
Ex: (A && B) is true.

Along the lines above, also in the same page, the one below is not giving what they said it would.

! (Logical NOT)
Reverses the logical state of its operand. If a condition is true, then the Logical NOT operator will make it false.
Ex: ! (A && B) is false.

document.write("!(a && b) => ");
result = (!(a && b));
document.write(result);
document.write(linebreak);

But it's giving me TRUE.

Also this one is not giving the expected result, in page 21:

<script>
<!--
var a = 10;
var b = 20;
var c = "Test";
var linebreak = "<br />";
a = a++;
document.write("a++ = ");
result = a++;
document.write(result);
document.write(linebreak);
b = b--;
document.write("b-- = ");
result = b--;
document.write(result);
document.write(linebreak);
//-->
</script>

 

[vacunita]

The first comparison is correctly returning false for me. Make sure both a and b are defined before you do the comparison.

As to the ++ issue. That's has always been confusing. The gist of it, is that a=a++, will assign the value of a before it increments a by 1.
Basically a++ returns a which is assigned to a. And then it adds 1 to a.

A better explanation here(though it may still not make sense):
Difference betwen a++ and ++a
You can perform the addition directly without assigning it, and the variable will be updated.

a++;
//no assignment.

Your other option is to change the order:

a=++a;

This will ad 1 to a first, and then assign the resulting value back to a.

----------------------------------
Phil AKA Vacunita
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OS-ception: Running Linux on a Virtual Machine in Windows which itself is running in a Virtual Machine on Mac OSx.

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