Message from JavaScript discussions

July 2017

— Like if you run var thing = "Hello" over and over, V8 actually will not re allocate memory for that string, it will re-use the existing one from memory...

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Now primitives are still copy-only, but until something edits the string it is very much the same exact memory location

— So if you can imagine... having knowledge of that during execution... powerful

— How is this a bad thing though?

— Oh, right

— We could say, for instance, that a variable assignment is the property of X scope, and do metaprogramming

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— And cross-scope, know exactly where it came from

— You could manage source code from a top-down perspective during runtime, idk the formal term but it would be like "self-aware JS"

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— Aaaah, like Lisp macros?

— A variable declaration is a directive to the parser to compute a scope and set a pointer to undefined for that variable until the line gets executed

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— So var thing = "hello", upon entry into a function call, runs code that allocates thing with undefined, then when it gets executed it simply swaps the pointer to the location in memory where the string is allocated

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— They're tagged pointers carrying the name of the variable, too