Discussion Topic: Var vs Const vs Let - Within Functions

[alishalabi]

(https://developer.mozilla.org/en-US/docs/Games/Tutorials/2D_Breakout_game_pure_JavaScript)

Context:
Throughout the course of this tutorial, I found converting all of the var variables with const or let variables (based on Airbnb's styleguide) was a great mental exercise . While many of these conversions were initially obvious (ex: Lives should almost always be let), many were not (ex: Should brickRowCount be let or const?).
Inevitably, for the less obvious variables - I found the best way to make a determination is to mentally go through your features and mentally identify which will change - shift those variable from (the default) const' to let`.

Discussion Point 1:
While the above method is thorough, it can take extra time. Are there any shortcuts used in industry to make a determination?

Discussion Point 2 :
How does this concept change when we are going through for loops?

Ex:

// Collision Detection (Brick)
    function collisionDetection() {
      for(var c=0; c<brickColumnCount; c++) {
        for(var r=0; r<brickRowCount; r++) {
          let b = bricks[c][r]
          if(b.status == 1) {
            if(x > b.x && x < b.x+brickWidth && y > b.y && y < b.y+brickHeight) {
              dy = -dy;
              b.status = 0;
              score++;
              if(score == brickRowCount*brickColumnCount) {
                alert("YOU WIN, YOU ROCK!")
                document.location.reload()
                clearInterval(interval)
              }
            }
          }
        }
      }
    }