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JavaScript jQuery Basics (2014) Creating a Simple Drawing Application Perform: Part 5

Rebecca Jensen
Rebecca Jensen
11,580 Points
Posted by Rebecca Jensen
Rebecca Jensen
11,580 Points

Entering 'lastEvent' in the console does not return a list for me

In this tutorial, 'lastEvent' is set to equal 'e' inside of a function, and 'lastEvent' listed as a constant at the top of the code ('const lastEvent;'). The teacher then opens the project, clicks on the canvas we're working on, then enters 'lastEvent' in the console to get a whole list of possible events (or something like that).

When I type 'lastEvent', I get "Uncaught ReferenceError: lastEvent is not defined at <anonymous>:1:1 ...VM16494:1"

Snapshot of my workspace is here: https://w.trhou.se/md9qutdmqa

Relevant code here:

const lastEvent;

//On mouse events on canvas
$canvas.mousedown(function(e){
  lastEvent = e;
});

Is something wrong in my code, or is this something browsers don't do anymore, or something else?

Rebecca Jensen
Rebecca Jensen
11,580 Points
Rebecca Jensen
Rebecca Jensen
11,580 Points

Aha. The instructor was using var, but var is either const or let these days, and I used const. But if I use let, it works!

1 Answer

edinjusupovic
edinjusupovic
5,664 Points
edinjusupovic
edinjusupovic
5,664 Points

VAR, LET and CONST are definitely not the same thing.

If you declare something with const, it will be immutable and cannot be modified; this is why when you declared lastEvent as a constant it didn't function as intended because in your code your function tries to overwrite lastEvent and this cannot be done with constant declarations.