function getOffset( el ) {    var _x = 0;    var _y = 0;    while( el && !isNaN( el.offsetLeft ) && !isNaN( el.offsetTop ) ) {        _x += el.offsetLeft - el.scrollLeft;        _y += el.offsetTop - el.scrollTop;        el = el.offsetParent;    }    return { top: _y, left: _x };}var x = getOffset( document.getElementById(‘yourElId‘) ).left;

通过javascript获取元素position