Js语言如下 不知道为什么没有动画效果

window.onload = function(){

var share = document.getElementById('share'),

content = document.getElementById('content');

share.onmouseover = function(){

share.style.backgroundColor = '#FF0';

shareFun();

};

}

var timer = null;

function shareFun (){

var share = document.getElementById('share'),

content = document.getElementById('content');

// clearInterval(timer);

timer = setInterval(function(){

content.style.left = (content.offsetLeft+10)+'px'; 

console.log(content.offsetLeft);

},30)

}