How to restrict my input type=“file” to accept onl

问题:

I am using input type="file", Now my requirement is that I only want to select png images, that is when I select browse a "png" filter should be applied.

I have referred www.w3schools.com/tags/att_input_accept.asp and below is the code I am using, this works fine with Chrome but does not work with Firefox and IE.

Please can anyone help me understand what wrong I must be doing ?

 <h2>Below uses accept="image/*"</h2>
 <input type="file" name="pic1" accept="image/*" /> 

 <h2>Below I need to accept only for png</h2>
 <input type="file" name="pic1" accept="image/png" /> 

​Here is a fiddle link to it http://jsfiddle.net/Jcgja/2/

回答1:

You need to validate it through java script. Below is the code for java script validation

function CheckFileName() {
        var fileName = document.getElementById("uploadFile").value
        if (fileName == "") {
            alert("Browse to upload a valid File with png extension");
            return false;
        }
        else if (fileName.split(".")[1].toUpperCase() == "PNG")
            return true;
        else {
            alert("File with " + fileName.split(".")[1] + " is invalid. Upload a validfile with png extensions");
            return false;
        }
        return true;
    }

回答2:

The browser support information on that page of w3schools is not correct.

If you check this page, you see that the accept attribute it's not implemented in Firefox:

https://developer.mozilla.org/en/HTML/Element/Input

Update:
The accept attribute is now implemented in Firefox, but users who don't have a recent version still won't have the support.

回答3:

As you can see, the 'accept' attribute is not properly supported by any of the major browsers. You could use a javascript validation on the form onsubmit event to verify if the file type is correct, returning false otherwise.

Do not use this attribute as a validation tool. File uploads should be validated on the server.

回答4:

<?php
if ((($_FILES["pic1"]["type"] == "image/png")
{
if ($_FILES["pic1"]["error"] > 0)
{
echo "Error: " . $_FILES["pic1"]["error"] . "<br />";
}
else
{
echo "Upload: " . $_FILES["pic1"]["name"] . "<br />";
echo "Type: " . $_FILES["pic1"]["type"] . "<br />";
echo "Size: " . ($_FILES["pic1"]["size"] / 1024) . " Kb<br />";
echo "Stored in: " . $_FILES["pic1"]["tmp_name"];
}
}
else
{
echo "Invalid file";
}
?>

This is just the validation of the type of file. Not the whole upload script.

回答5:

you can use javascript function onChane event of a file function

filesChange() {
        checkFile();
        } 
<script type="text/javascript">
function checkFile() {
    var fileElement = document.getElementById("uploadFile");
    var fileExtension = "";
    if (fileElement.value.lastIndexOf(".") > 0) {
        fileExtension = fileElement.value.substring(fileElement.value.lastIndexOf(".") + 1, fileElement.value.length);
    }
    if (fileExtension == "gif") {
        return true;
    }
    else {
        alert("You must select a GIF file for upload");
        return false;
    }
}

回答6:

As pointed out in the comments, accepted solution won't work with a file name with several "." in it. This should handle it better, it is more bug-proof and flexible, and you can manage accepted extensions by editing the array.

function checkFileExtension() {
    var fileName = document.getElementById("uploadFile").value;

    if(!fileName)
      return false;

    var extension = fileName.split(".");
    if(extension && extension.length > 1){
        extension = [extension.length-1].toUpperCase();
        if (["PNG"].indexOf(extension) != -1)
            return true;
        else{
            alert("Browse to upload a valid File with png extension");
            return false;
        }
    }
    else{
        alert("Browse to upload a valid File with png extension");
        return false;
    }
}