带有动画效果的滚动

Question

我需要使用动画效果来执行javascript中的scrollTo(x, y)方法。我不能使用jQuery来实现。

- Alex

Answer 1

[Working demo]

function interpolate( source,target,pos ) { 
  return ( source + (target - source) * pos ); 
}

function easing( pos ) { 
    return ( -Math.cos( pos * Math.PI ) / 2 ) + 0.5; 
}

function scrollTop( duration ) {

  duration = duration || 1000;

  var startY = window.pageYOffset,
      start  = Number(new Date()),
      finish = start + duration;

  var interval = setInterval(function() {

    var now = Number(new Date()),
        pos = (now > finish) ? 1 : (now - start) / duration;

     scrollTo(0, interpolate( startY, 0, easing(pos) ));

     if ( now > finish )
       clearInterval( interval );
  }, 15);
};

- gblazex

Answer 2

你可以使用window.setTimeout()和window.clearTimeout()函数调用来在Javascript中动画化（几乎）任何东西。请参见http://www.w3schools.com/js/js_timing.asp。

- user335938