- Define g and s as parameter even though they're only given a value inside the function
- Pass document into the function instead of using it from global scope
- Insert a script tag in front of the other script tags on-the-fly using insertBefore, instead of simply doing <script async src="...">...</script>
Pretty interesting. Care to explain a bit?
Creating a new script tag with JS lets you get asynchronous script loading for older browsers that don't support the async attribute.
Some other ways to reduce bytes are outlined at https://github.com/jed/140bytes/wiki/Byte-saving-techniques
"As for your question, we pass in `document` that way to prevent unnecessary scope lookups. We could’ve used `var d = document` inside the IIFE, but that would trigger an additional scope lookup. For `'script'` it doesn’t matter; you could initialize that inside of the IIFE if you want."
Perhaps if this was inside a tight inner loop, I could understand, but here it's completely unneccessary.
Then again, Javascript is a strange animal here as the code is provided to the execution environment as plaintext instead of bytecode/assembly. I guess a JS-to-JS compiler such as closure could handle it.
- Define g and s as parameter even though they're only given a value inside the function
- Pass document into the function instead of using it from global scope
This is not necessarily true: javascript passed arguments by reference, and thus g and s are actually "given back" to the caller, who can then do different things with those objects.
d is not necessarily a document, but can be something different too: consider, for example, the contentWindow of an iframe.
Pass by reference doesn't work that way in JS;
function a(b) { b = 10; }
var foo;
a(foo);
alert(foo);
Then the only thing I can think about is that accepting it as an additional parameter in the function call is less overhead (as in, bytes) than defining 'b' as a var:
function a(b)
{
b = 10;
}
function a()
{
var b = 10;
}
EDIT: I see dave1010uk also said this.