Explanation
“@instance:” allows us to attach an object/value to the Foo class instead of Foo’s prototype. Recall that “@” in CoffeeScript refers to JavaScript’s “this”.
After “@instance:” there is a function that is immediately executed. This function returns a function, closed around a variable called instance. Both these functions have their context (their “this”) bound to the Foo object using CoffeeScript’s wonderful “define and bind” operator “=>” as opposed to the normal function definition operator “->”.
When called, the function that “@instance” ends up referring to simply checks to see if the “instance” variable is empty and if so, assigns a new instance of Foo to it. Newing up a Foo is done using the “@” symbol since the function’s “this” refers to the Foo object. It then returns the instance.
Output
The CoffeeScript above compiles down to this:
Window installation is one of those jobs where shortcuts come back to bite you—and your heating bill—all winter long. Common mistakes I see often start with measuring. Folks either measure the rough opening or the existing trim, but not both bedroom window code
Been through a couple of window replacements in the US, so here’s what I’ve learned. First, costs vary a lot, but expect $300-$700 per window installed for decent quality — anything cheaper, you’re probably cutting corners on materials or labor https://emilianorcta375.image-perth.org/when-homeowners-budget-for-new-windows-sarah-s-story