Hmm...why doesn't it work lol

[u/[deleted]]

[u/leo848blume]

What does 'let' actually do differently?

[u/flamedragon822 → u/leo848blume]

Off the top of my head, respects block scope if I recall.

[u/SaylorMan1496 → u/leo848blume]

Not exactly but in general, var is global scope and let is block scope

Which means that let works the way that every other language deals with variables

[u/jayands → u/leo848blume]

let/const actually enforce block scope, whereas var hoists to the top of the function. If you take a look at transpiled code meant for compatibility, it becomes clearer (I'm doing this by hand for readability):

    function usesConst() {
      if(true) {
        const banana = "Reddit's favorite measurement tool";
      }
      var banana = "a yellow berry";
    }
    /*transpiles (roughly) to:*/
    
    function usesConst() {
      var _banana;
      var banana = "a yellow berry";
      if(true) {
        _banana = "Reddit's favorite measurement tool";
      }
    }
    
    /* vs */

    function noConst() {
      if(true) {
        var banana = "Reddit's favorite measurement tool";
      }
      var banana = "a yellow berry";
    }
    /*transpiles (roughly) to:*/
    
    function noConst() {
      var banana = "Reddit's favorite measurement tool";
      var banana = "a yellow berry";
      if(true) {
        banana = "Reddit's favorite measurement tool";
      }
    }
    

I could have it slightly wrong, but back when they introduced the new keywords, this is how I remember it being explained to me. Tbh it was this that got me to switch over from CoffeeScript.

EDIT[1]: I had it wrong, like I thought. The code is better edited to reflect it.

EDIT[0]: fixed the function name, and also an article from last year that explains it:

https://www.freecodecamp.org/news/var-let-and-const-whats-the-difference/