在客户端的 Chrome 中使用 Javascript 创建文件

Question

I would like to know if I can create a text file and save the file in the users "Downloads" section in his/her computer using Javascript. The way my feature should work is when the user clicks the submit button, I populate the users info in the text file and then save it in his machine. I would like this to work in Google Chrome.

Is this possible? I have seen posts that specifically tell me that it is a serious security issue.

Answer 1

Sure you can, using the brand new APIs.

 window.requestFileSystem = window.requestFileSystem || window.webkitRequestFileSystem;

 window.requestFileSystem(window.TEMPORARY, 1024*1024, function(fs) {
    fs.root.getFile('test.bin', {create: true}, function(fileEntry) { // test.bin is filename
        fileEntry.createWriter(function(fileWriter) {
            var arr = new Uint8Array(3); // data length

            arr[0] = 97; // byte data; these are codes for 'abc'
            arr[1] = 98;
            arr[2] = 99;

            var blob = new Blob([arr]);

            fileWriter.addEventListener("writeend", function() {
                // navigate to file, will download
                location.href = fileEntry.toURL();
            }, false);

            fileWriter.write(blob);
        }, function() {});
    }, function() {});
}, function() {});

Answer 2

Enter this into the Chrome browser

data:text;charset=utf-8,helloWorld

So to construct the download for your users you would do something like

data='<a href='data:text;charset=utf-8,'+uriEncode(yourUSERdataToDownload)+' >Your Download</a>

Then inject it into the dom for your user to press.

Answer 3

The following method works in IE11+, Firefox 25+ and Chrome 30+:

<a id="export" class="myButton" download="" href="#">export</a>
<script>
    function createDownloadLink(anchorSelector, str, fileName){
        if(window.navigator.msSaveOrOpenBlob) {
            var fileData = [str];
            blobObject = new Blob(fileData);
            $(anchorSelector).click(function(){
                window.navigator.msSaveOrOpenBlob(blobObject, fileName);
            });
        } else {
            var url = "data:text/plain;charset=utf-8," + encodeURIComponent(str);
            $(anchorSelector).attr("download", fileName);               
            $(anchorSelector).attr("href", url);
        }
    }

    $(function () {
        var str = "hi,file";
        createDownloadLink("#export",str,"file.txt");
    });

</script>

See this in Action: http://jsfiddle.net/Kg7eA/

Firefox and Chrome support data URI for navigation, which allows us to create files by navigating to a data URI, while IE doesn't support it for security purposes.

On the other hand, IE has API for saving a blob, which can be used to create and download files.

Answer 4

Try this:

document.body.innerHTML+="<a id='test' href='data:text;charset=utf-8,"+encodeURIComponent("hi")+"'>Your Download</a>";
document.getElementById('test').click();

if you want to set the filename use download attribute of anchor tag:

document.body.innerHTML+="<a id='test' href='data:text;charset=utf-8,"+encodeURIComponent("hi")+"' download=yourfilename>Your Download</a>";
document.getElementById('test').click();

Answer 5

No, as that would allow you to create malicious programs in the client's computer, and harm his privacy.

Also, requests to download files come from the server, so you'll need to create the file on the server, and serve it to the user, and hope he'll save it (if he requested for it it's likely that he will).

Another possible solution to look at is to use data URIs or CSVs, but browser support for them is incomplete (IE), see Create a file in memory for user to download, not through server

Answer 6

You will need server side functionality in order to server the user a text file (javascript is not enough). You can create a server side script that creates the file and use javascript in order to prompt user to save it.

Answer 7

在用户提交按钮上，您可以在服务器上创建文件并将用户重定向到文件的 url，从那里它应该自动下载。

Answer 8

var isIE = /*@cc_on!@*/ false || !! document.documentMode; // At least IE6
var uri = "some data"; //data in file
var fileName = "file.i4cvf"; // any file name with any extension
if (isIE) {
    var fileData = ['\ufeff' + uri];
    var blobObject = new Blob(fileData);
    window.navigator.msSaveOrOpenBlob(blobObject, fileName);
} else //chrome
{
    window.requestFileSystem = window.requestFileSystem || window.webkitRequestFileSystem;
    window.requestFileSystem(window.TEMPORARY, 1024 * 1024, function (fs) {
        fs.root.getFile(fileName, {
            create: true
        }, function (fileEntry) {
            fileEntry.createWriter(function (fileWriter) {
                var fileData = ['\ufeff' + uri];
                var blob = new Blob(fileData);
                fileWriter.addEventListener("writeend", function () {
                    var fileUrl = fileEntry.toURL();
                    var link = document.createElement('a');
                    link.href = fileUrl;
                    link.download = fileName;
                    document.body.appendChild(link);
                    link.click();
                    document.body.removeChild(link);
                }, false);
                fileWriter.write(blob);
            }, function () {});
        }, function () {});
    }, function () {});
}

Answer 9

This link helped me a lot and solved my problem. Cross browser solution:

https://www.thewebflash.com/reading-and-creating-text-files-using-the-html5-file-api/

This is the most relevant part:

if ('msSaveOrOpenBlob' in navigator) {

    navigator.msSaveOrOpenBlob(textFileAsBlob, fileName);
} else {
    var downloadLink = document.createElement('a');
    downloadLink.download = fileName;
    downloadLink.innerHTML = 'Download File';
    if ('webkitURL' in window) {
        // Chrome allows the link to be clicked
        // without actually adding it to the DOM.
        downloadLink.href = window.webkitURL.createObjectURL(textFileAsBlob);
    } else {
        // Firefox requires the link to be added to the DOM
        // before it can be clicked.
        downloadLink.href = window.URL.createObjectURL(textFileAsBlob);
        downloadLink.onclick = destroyClickedElement;
        downloadLink.style.display = 'none';
        document.body.appendChild(downloadLink);
    }

    downloadLink.click();
}