Vector class is a powerful class introduced with flash player 10. It is fundamentally a special typed array into which all elements must be the same type and it is faster than a normal Array.

What you maybe don’t know:

It’s possible to initialize a Vector with an Array or another Vector as a source but you must use the Vector function not the class constructor. The class constructor in fact has the following signature:

Vector function instead has this:

So, rather than using such approach:

We can do the following (Notice the absence of “this” keyword):

var buffer = [];
var target = document.getElementById("box");

for (var i=0; i<10000; i++) {
    buffer .push(['<p id="node_', i, '" id="node_', i, '">Content ', i, '</p>'].join(""));
}

target.innerHTML = buffer.join("");

This is theoretically the fastest way to manage huge strings and to speed up the building of dynamic content.

It’s been a long time since I used this technique, but today I was doing some tests and I’ve realized that is not obsolete, but somehow inadequate to some modern browsers (Firefox 3, Opera 9 and Google Chrome), due to the worst performance compared to the old and classic string concatenation technique with the plus (+) operator. In my test I’ve compared the time required to concatenate a string built in a 10.000 steps loop with the time required to filling an array, and the amazing result is that, except for internet explorer (for the which buffer technique improve a lot the browser performance) and safari 3, other browser run faster with normal string concatenation with +… even 70/80% faster!
The results are the following:

- String concatenation with +:

• 17000 milliseconds on Internet Explorer 6
• 17000 milliseconds on Internet Explorer 7
• 265 milliseconds on Opera 9
• 125 milliseconds on Firefox 3
• 165 milliseconds on Safari 3
• 50 milliseconds on Google Chrome

- Array based technique:

• 530 milliseconds on Internet Explorer 6 -> -16470 milliseconds (damned good!)
• 470 milliseconds on Internet Explorer 7 -> -16530 milliseconds (damned good!)
• 450 milliseconds on Opera 9 -> +185  milliseconds (very bad!)
  
• 200 milliseconds on Firefox 3 -> +75 milliseconds (bad!)
• 145 milliseconds on Safari 3 -> -20 milliseconds (good)
  
• 95 milliseconds on Google Chrome -> +45 milliseconds (bad)

In conclusion:  if we want to get the best performances from Firefox, Opera and Chrome we have to avoid the array based technique (and use “+” operator instead),  however this technique is still valid if we don’t want to import a browser specific javascript file or branch the code from one browser to another, because it enhance meaningfully the code execution speed of Internet Explorer and decrease in an acceptable manner the execution on other browsers.