var clicked = false;

function toggleBtnClick() {
  var img = document.getElementById('baseImg');
  if (clicked) {
    img.src = 'http://via.placeholder.com/350x150/e9e9e9/000000';
    clicked = false;
  } else {
    img.src = 'http://via.placeholder.com/350x150/3fafed/000000';
    clicked = true;
  }
}