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Unroll your loops

do {

//do something here

i++;

} while (i < aValues.length);

This code now runs faster than using the

while

loop, but it can be optimized further by reversing the loop:

var i=aValues.length-1;

do {

//do something here

i--;

} while (i >= 0);

You can also eliminate an extra statement by putting the decrement into the control statement directly:

var i=aValues.length-1;

do {

//do something here

} while (i-- >= 0);

The loop has now been fully optimized for execution speed.

Unroll your loops

Instead of using loops that execute one statement each time through, you can

unroll

these loops to run

multiple statements. Consider the following simple

for

loop:

var aValues = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20];

var iSum = 0;

for (var i=0; i < aValues.length; i++) {

iSum += aValues[i];

}

This loop body executes 20 times, each time adding to the variable

iSum

. This is a fairly simple opera-

tion, so it’s possible to unroll this operation and execute it several times within the

for

loop:

var aValues = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20];

var iSum = 0;

for (var i=0; i < aValues.length; i++) {

iSum += aValues[i];

i++;

iSum += aValues[i];

i++;

iSum += aValues[i];

i++;

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Deployment Issues

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