在上传文件之前使用Javascript显示图像和图像扩展的验证

Question

我的目标是首先验证上传文件是图像,如果是图像,我将显示它.我从验证码和图像代码中获取代码.

起初我能够显示图像.但是,当我将显示图像代码与验证代码相结合时,我无法同时验证和显示工作.

谁能帮帮我吗？以下是我的代码.提前致谢!:)

<input type="file" name="dataFile" id="fileChooser" onchange="readURL(this);" />





<SCRIPT type="text/javascript">

var _validFileExtensions = [".jpg", ".jpeg", ".bmp", ".gif", ".png"];

     function readURL(input) {

         var arrInputs = document.getElementById("fileChooser").value;
            for (var i = 0; i < arrInputs.length; i++) {
                var oInput = arrInputs[i];
                if (oInput.type == "file") {
                    var sFileName = oInput.value;
                if (sFileName.length > 0) {
                    var blnValid = false;
                    for (var j = 0; j < _validFileExtensions.length; j++) {
                        var sCurExtension = _validFileExtensions[j];
                        if (sFileName.substr(sFileName.length - sCurExtension.length, sCurExtension.length).toLowerCase() == sCurExtension.toLowerCase()) {
                            blnValid = true;

                            if (input.files && input.files[0])  {
                                var reader = new FileReader();

                                reader.onload = function (e) {
                                    $('#blah').attr('src', e.target.result)
                                };

                                reader.readAsDataURL(input.files[0]);
                            }


                            break;
                        }
                    }

                    if (!blnValid) {
                        alert("Sorry, " + sFileName + " is invalid, allowed extensions are: " + _validFileExtensions.join(", "));
                        return false;
                    }
                }
            }
        }

        return true;





    }

Answer 1

我能够解决它.下面是正确的代码.:)

JavaScript的

<SCRIPT type="text/javascript">
    function ValidateFileUpload() {
        var fuData = document.getElementById('fileChooser');
        var FileUploadPath = fuData.value;

//To check if user upload any file
        if (FileUploadPath == '') {
            alert("Please upload an image");

        } else {
            var Extension = FileUploadPath.substring(
                    FileUploadPath.lastIndexOf('.') + 1).toLowerCase();

//The file uploaded is an image

if (Extension == "gif" || Extension == "png" || Extension == "bmp"
                    || Extension == "jpeg" || Extension == "jpg") {

// To Display
                if (fuData.files && fuData.files[0]) {
                    var reader = new FileReader();

                    reader.onload = function(e) {
                        $('#blah').attr('src', e.target.result);
                    }

                    reader.readAsDataURL(fuData.files[0]);
                }

            } 

//The file upload is NOT an image
else {
                alert("Photo only allows file types of GIF, PNG, JPG, JPEG and BMP. ");

            }
        }
    }
</SCRIPT>

改变的输入:

<input type="file" name="dataFile" id="fileChooser" onchange="return ValidateFileUpload()" />

要在上传之前显示图像:

<img src="images/noimg.jpg" id="blah">