前端上传图片文件转base64

html:

<input accept="image/gif,image/jpeg,image/jpg,image/png" type="file" id="up" />

js

      $(function() {
            $("#up").change(function() {
                    var file = this.files[0];
                    if(undefined == file){
                        return ;
                    }
                    var r = new FileReader(); 
                    r.readAsDataURL(file); 
                    r.onload = function(e) {
                        var base64 = e.target.result;
                        
                    }
                });
            });