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Shorten negative tests

Consider this example:

var bFound = false;

for (var i=0; i < aTest.length && !bFound; i++) {

if (aTest[i] == vTest) {

bFound = true;

}

You can replace the

true

and

false

without changing the meaning:

var bFound = 0;

for (var i=0; i < aTest.length && !bFound; i++) {

if (aTest[i] == vTest) {

bFound = 1;

}

This code runs exactly the same way, and you’ve gained seven bytes.

Shorten negative tests

It’s quite common to test whether a value is valid. The most these

negative tests

can do is determine if a

variable is equal (or not equal) to

undefined

null

, or

false

, such as in the following:

if (oTest != undefined) {

//do something

}

if (oTest != null) {

//do something

}

if (oTest != false) {

//do something

}

These are all fine, but they can all be rewritten using the logical NOT operator and have the exact same

effect:

if (!oTest) {

//do something

}

How is this possible? Remember way back at the beginning of the book when automatic type conver-

sions were discussed? The NOT operator returns

true

when its operand is

undefined

null

, or

false

(it also returns

true

if the operand is

). Take a look at the byte savings anytime you replace one of these

negative tests with the logical NOT operator.

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