What’s going on? You say: feel like there is nothing special is going on here. The outer foo in bar increments the global x, and foo surrounded by let in bar increments the shadowed x. What’s the big deal? The special that’s going on here is that LET can shadow the value of *x*. With … Read more
As already stated in this comment and this answer, this does not have a different meaning between JavaScript and TypeScript. That being said, your problem here is way more prosaic: you’re trying to use this in an arrow function to get the current DOM element, and that will simply not work. So, in a nutshell, … Read more
The $ allows you extract elements by name from a named list. For example x <- list(a=1, b=2, c=3) x$b # [1] 2 You can find the names of a list using names() names(x) # [1] “a” “b” “c” This is a basic extraction operator. You can view the corresponding help page by typing ?Extract … Read more
Unlike in a language like Python, a Javascript method forgets it is a method after you extract it and pass it somewhere else. You can either Wrap the method call inside an anonymous function This way, accessing the baz property and calling it happen at the same time, which is necessary for the this to … Read more
<<- is most useful in conjunction with closures to maintain state. Here’s a section from a recent paper of mine: A closure is a function written by another function. Closures are so-called because they enclose the environment of the parent function, and can access all variables and parameters in that function. This is useful because … Read more
I understand them through examples. 🙂 First, lexical scope (also called static scope), in C-like syntax: void fun() { int x = 5; void fun2() { printf(“%d”, x); } } Every inner level can access its outer levels. There is another way, called dynamic scope used by the first implementation of Lisp, again in a … Read more