JS获取图片的原始宽度和高度，兼容IE7,8

// 封装
function getNaturalSize (DomElement) {
    var natureSize = {};
    if(window.naturalWidth && window.naturalHeight) {
        natureSize.width = DomElement.naturalWidth;
        natureSizeheight = DomElement.naturalHeight;
    } else {
       var img = new Image();
        img.src = DomElement.src;
        natureSize.width = img.width;
        natureSizeheight = img.height;
    }
    return natureSize;
}
  
// 使用
var natural = getNaturalSize (document.getElementById(‘img‘)),
    natureWidth = natural.width,
    natureHeight = natural.height;