js提交图片转换为base64

$("#picAjax").change(function () {
var strs = "";
var file = $("#picAjax").get(0).files[0];
var reader = new FileReader();
reader.readAsDataURL(file);
reader.onloadend = function () {
strs = reader.result;
$("#selImg").attr({ "src": strs });
}
});