Simple shake animation for TweenMax (gsap.js). For modern form error feedback.

shake.js

function shakeAnimation(element){
  TweenMax.to(element, .1, {
    x: -7,
    ease: Quad.easeInOut
  });
  TweenMax.to(element, .1, {
    repeat: 4,
    x: 7,
    yoyo: true,
    delay: .1,
    ease: Quad.easeInOut
  });
  TweenMax.to(element, .1, {
    x: 0,
    delay: .1 * 4
  });
}