JavaScript函数未注册按键

Question

I'm trying to get a function to stop when the enter key is pressed but for some reason it is not registering my enter variable's switch from false to true. I don't know if this is a scope issue or a closure issue or a binding issue, I've looked throughout the forums and tried a bunch of different solutions but nothing seems to work...

function positionArrow(arrow) {
  var enter = false;
  $(document).keypress(function(e) {
      if(e.which == 13) {
        enter = true;
      }
  });
  console.log(enter);
  if (enter == true) {
    return;
  } else {
    $(arrow.element).css({
        left: arrow.x - arrowWidth / 2,
        top: arrow.y - arrowHeight / 2
      });
    rotate(arrow.element, arrow.angle);
  }
}

Answer 1

You should have the code you want to run within your handler, and also your handler should be outside of your "positionArrow" function. Try replacing enter = true; with

$(arrow.element).css({
    left: arrow.x - arrowWidth / 2,
    top: arrow.y - arrowHeight / 2
});
rotate(arrow.element, arrow.angle);

And moving your handler declaration outside of the function. Code should look like this

  $(document).keypress(function(e) {
      if(e.which == 13) {
        positionArrow(arrow);
      }
  }
  function positionArrow(arrow) {
    $(arrow.element).css({
        left: arrow.x - arrowWidth / 2,
        top: arrow.y - arrowHeight / 2
      });
    rotate(arrow.element, arrow.angle);
   }

Answer 2

I managed to get it to work with the method below. I made enter a global variable and created a separate function. While this works, I feel there may be a better solution out there or a better articulation of what the problem was to begin with.

var enter = false;    

function stopArrow(){
    $(document).keypress(function(e) {
        if(e.which == 13) {
          enter = true;
        }
    });
}

stopArrow();

function positionArrow(arrow) {
  if (enter == true) {
    return;
  } else {
    $(arrow.element).css({
        left: arrow.x - arrowWidth / 2,
        top: arrow.y - arrowHeight / 2
      });
    rotate(arrow.element, arrow.angle);
  }
}