在js中获取上传图片的宽度和高度

Html：

<input type="file" id="MapUploadTd" onchange="getMapPictureSize(this.files[0])"/>

Js：

var mapPictureSize = [];

function getMapPictureSize(file) {
    var reader = new FileReader;
    reader.onload = function (evt) {
        var image = new Image();
        image.onload = function () {
            mapPictureSize[0] = this.width + "";
            mapPictureSize[1] = this.height + "";
            console.log(mapPictureSize);
        };
        image.src = evt.target.result;
    };
    reader.readAsDataURL(file);
}