Based on http://html5-demos.appspot.com/static/a.download.html: (archived)
var fileContent = "My epic novel that I don't want to lose.";
var bb = new Blob([fileContent ], { type: 'text/plain' });
var a = document.createElement('a');
a.download = 'download.txt';
a.href = window.URL.createObjectURL(bb);
a.click();
Modified the original fiddle: http://jsfiddle.net/9av2mfjx/
Answer from Stanislav on Stack OverflowBased on http://html5-demos.appspot.com/static/a.download.html: (archived)
var fileContent = "My epic novel that I don't want to lose.";
var bb = new Blob([fileContent ], { type: 'text/plain' });
var a = document.createElement('a');
a.download = 'download.txt';
a.href = window.URL.createObjectURL(bb);
a.click();
Modified the original fiddle: http://jsfiddle.net/9av2mfjx/
You should check the download attribute and the window.URL method because the download attribute doesn't seem to like data URI.
This example by Google is pretty much what you are trying to do.
html - Is it possible to write data to file using only JavaScript? - Stack Overflow
Save a string to a local file - Post.Byes
javascript - How to generate and prompt to save a file from content in the client browser? - Stack Overflow
angularjs - capture and save string to local file - Stack Overflow
You can create files in browser using Blob and URL.createObjectURL. All recent browsers support this.
You can not directly save the file you create, since that would cause massive security problems, but you can provide it as a download link for the user. You can suggest a file name via the download attribute of the link, in browsers that support the download attribute. As with any other download, the user downloading the file will have the final say on the file name though.
var textFile = null,
makeTextFile = function (text) {
var data = new Blob([text], {type: 'text/plain'});
// If we are replacing a previously generated file we need to
// manually revoke the object URL to avoid memory leaks.
if (textFile !== null) {
window.URL.revokeObjectURL(textFile);
}
textFile = window.URL.createObjectURL(data);
// returns a URL you can use as a href
return textFile;
};
Here's an example that uses this technique to save arbitrary text from a textarea.
If you want to immediately initiate the download instead of requiring the user to click on a link, you can use mouse events to simulate a mouse click on the link as Lifecube's answer did. I've created an updated example that uses this technique.
var create = document.getElementById('create'),
textbox = document.getElementById('textbox');
create.addEventListener('click', function () {
var link = document.createElement('a');
link.setAttribute('download', 'info.txt');
link.href = makeTextFile(textbox.value);
document.body.appendChild(link);
// wait for the link to be added to the document
window.requestAnimationFrame(function () {
var event = new MouseEvent('click');
link.dispatchEvent(event);
document.body.removeChild(link);
});
}, false);
Some suggestions for this -
- If you are trying to write a file on client machine, You can't do this in any cross-browser way. IE does have methods to enable "trusted" applications to use ActiveX objects to read/write file.
- If you are trying to save it on your server then simply pass on the text data to your server and execute the file writing code using some server side language.
- To store some information on the client side that is considerably small, you can go for cookies.
- Using the HTML5 API for Local Storage.
This "FileSaver" library may help. If you want it to be reasonably cross-browser, you'll also need this to implement the W3C Blob API in places it's not already implemented. Both respect namespaces, and are completely framework agnostic, so don't worry about naming issues.
Once you've got those included, and as long as you're only saving text files, you should be able to
var blob = new Blob(["Hello, world!"], {type: "text/plain;charset=utf-8"});
saveAs(blob, "hello world.txt");
Note that the first argument to new Blob has to be a list of strings, and that you're expected to specify the filename. As in, the user will see this file being downloaded locally, but won't be able to name it themselves. Hopefully they're using a browser that handles local filename collisions...
This is my code:
<a id='tfa_src_data'>Export</a>
document.getElementById('tfa_src_data').onclick = function() {
var csv = JSON.stringify(localStorage['savedCoords']);
var csvData = 'data:application/csv;charset=utf-8,'
+ encodeURIComponent(csv);
this.href = csvData;
this.target = '_blank';
this.download = 'filename.txt';
};
You can use various data types.
You can just use the Blob function:
function save() {
var htmlContent = ["your-content-here"];
var bl = new Blob(htmlContent, {type: "text/html"});
var a = document.createElement("a");
a.href = URL.createObjectURL(bl);
a.download = "your-download-name-here.html";
a.hidden = true;
document.body.appendChild(a);
a.innerHTML = "something random - nobody will see this, it doesn't matter what you put here";
a.click();
}
and your file will save.
Chromium's File System Access API (introduced in 2019)
There's a relatively new, non-standard File System Access API (not to be confused with the earlier File and Directory Entries API or the File System API). It looks like it was introduced in 2019/2020 in Chromium/Chrome, and doesn't have support in Firefox or Safari.
When using this API, a locally opened page can open/save other local files and use the files' data in the page. It does require initial permission to save, but while the user is on the page, subsequent saves of specific files do so 'silently'. A user can also grant permission to a specific directory, in which subsequent reads and writes to that directory don't require approval. Approval is needed again after the user closes all the tabs to the web page and reopens the page.
You can read more about this newish API at https://web.dev/file-system-access/. It's meant to be used to make more powerful web applications.
A few things to note about it:
By default, it requires a secure context to run. Running it on https, localhost, or through file:// should work.
You can get a file handle from dragging and dropping a file by using DataTransferItem
.getAsFileSystemHandleInitially reading or saving a file requires user approval and can only be initiated via a user interaction. After that, subsequent reads and saves don't need approval, until the site is opened again.
Handles to files can be saved in the page (so if you were editing local file
'/path/to/file.txt', and reload the page, it would be able to have a reference to the file). They can't seemingly be stringified, so are stored through something like IndexedDB (see this answer for more info). Using stored handles to read/write requires user interaction and user approval.
Here are some simple examples. They don't seem to run in a cross-domain iframe, so you probably need to save them as an html file and open them up in Chrome/Chromium.
Opening and Saving, with Drag and Drop (no external libraries):
<body>
<div><button id="open">Open</button><button id="save">Save</button></div>
<textarea id="editor" rows=10 cols=40></textarea>
<script>
let openButton = document.getElementById('open');
let saveButton = document.getElementById('save');
let editor = document.getElementById('editor');
let fileHandle;
async function openFile() {
try {
[fileHandle] = await window.showOpenFilePicker();
await restoreFromFile(fileHandle);
} catch (e) {
// might be user canceled
}
}
async function restoreFromFile() {
let file = await fileHandle.getFile();
let text = await file.text();
editor.value = text;
}
async function saveFile() {
var saveValue = editor.value;
if (!fileHandle) {
try {
fileHandle = await window.showSaveFilePicker();
} catch (e) {
// might be user canceled
}
}
if (!fileHandle || !await verifyPermissions(fileHandle)) {
return;
}
let writableStream = await fileHandle.createWritable();
await writableStream.write(saveValue);
await writableStream.close();
}
async function verifyPermissions(handle) {
if (await handle.queryPermission({ mode: 'readwrite' }) === 'granted') {
return true;
}
if (await handle.requestPermission({ mode: 'readwrite' }) === 'granted') {
return true;
}
return false;
}
document.body.addEventListener('dragover', function (e) {
e.preventDefault();
});
document.body.addEventListener('drop', async function (e) {
e.preventDefault();
for (const item of e.dataTransfer.items) {
if (item.kind === 'file') {
let entry = await item.getAsFileSystemHandle();
if (entry.kind === 'file') {
fileHandle = entry;
restoreFromFile();
} else if (entry.kind === 'directory') {
// handle directory
}
}
}
});
openButton.addEventListener('click', openFile);
saveButton.addEventListener('click', saveFile);
</script>
</body>
Storing and Retrieving a File Handle using idb-keyval:
Storing file handles can be tricky, since they can't be unstringified, though apparently they can be used with IndexedDB and mostly with history.state. For this example we'll use idb-keyval to access IndexedDB to store a file handle. To see it work, open or save a file, and then reload the page and press the 'Restore' button. This example uses some code from https://stackoverflow.com/a/65938910/.
<body>
<script src="https://unpkg.com/idb-keyval@6.1.0/dist/umd.js"></script>
<div><button id="restore" style="display:none">Restore</button><button id="open">Open</button><button id="save">Save</button></div>
<textarea id="editor" rows=10 cols=40></textarea>
<script>
let restoreButton = document.getElementById('restore');
let openButton = document.getElementById('open');
let saveButton = document.getElementById('save');
let editor = document.getElementById('editor');
let fileHandle;
async function openFile() {
try {
[fileHandle] = await window.showOpenFilePicker();
await restoreFromFile(fileHandle);
} catch (e) {
// might be user canceled
}
}
async function restoreFromFile() {
let file = await fileHandle.getFile();
let text = await file.text();
await idbKeyval.set('file', fileHandle);
editor.value = text;
restoreButton.style.display = 'none';
}
async function saveFile() {
var saveValue = editor.value;
if (!fileHandle) {
try {
fileHandle = await window.showSaveFilePicker();
await idbKeyval.set('file', fileHandle);
} catch (e) {
// might be user canceled
}
}
if (!fileHandle || !await verifyPermissions(fileHandle)) {
return;
}
let writableStream = await fileHandle.createWritable();
await writableStream.write(saveValue);
await writableStream.close();
restoreButton.style.display = 'none';
}
async function verifyPermissions(handle) {
if (await handle.queryPermission({ mode: 'readwrite' }) === 'granted') {
return true;
}
if (await handle.requestPermission({ mode: 'readwrite' }) === 'granted') {
return true;
}
return false;
}
async function init() {
var previousFileHandle = await idbKeyval.get('file');
if (previousFileHandle) {
restoreButton.style.display = 'inline-block';
restoreButton.addEventListener('click', async function (e) {
if (await verifyPermissions(previousFileHandle)) {
fileHandle = previousFileHandle;
await restoreFromFile();
}
});
}
document.body.addEventListener('dragover', function (e) {
e.preventDefault();
});
document.body.addEventListener('drop', async function (e) {
e.preventDefault();
for (const item of e.dataTransfer.items) {
console.log(item);
if (item.kind === 'file') {
let entry = await item.getAsFileSystemHandle();
if (entry.kind === 'file') {
fileHandle = entry;
restoreFromFile();
} else if (entry.kind === 'directory') {
// handle directory
}
}
}
});
openButton.addEventListener('click', openFile);
saveButton.addEventListener('click', saveFile);
}
init();
</script>
</body>
Additional Notes
Firefox and Safari support seems to be unlikely, at least in the near term. See https://github.com/mozilla/standards-positions/issues/154 and https://lists.webkit.org/pipermail/webkit-dev/2020-August/031362.html
(preferably without the full path, just filename since in same folder as html)
because local storage get's deleted on browser clear...
if there is no way to do it, what's the alternative?
could i save it in google sheet?
Save to filesystem
Have a look at angular-file-saver
Or use the following code as a reference in saving a BLOB. Where the blob object is generated from a JSON Object. But extration to a TEXT file is also possible.
// export page definition to json file
$scope.exportToFile = function(){
var filename = 'filename'
var blob = new Blob([angular.toJson(object, true)], {type: 'text/plain'});
if (window.navigator && window.navigator.msSaveOrOpenBlob) {
window.navigator.msSaveOrOpenBlob(blob, filename);
} else{
var e = document.createEvent('MouseEvents'),
a = document.createElement('a');
a.download = filename;
a.href = window.URL.createObjectURL(blob);
a.dataset.downloadurl = ['text/json', a.download, a.href].join(':');
e.initEvent('click', true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
a.dispatchEvent(e);
// window.URL.revokeObjectURL(a.href); // clean the url.createObjectURL resource
}
}
Using LocalStorage
Saving to localStorage:
window.localStorage.setItem('key', value);
Getting from localStorage
window.localStorage.getItem('key');
Delete key from localStorage
window.localStorage.removeItem('key');
Or using the AngularJS module 'ngStorage'
Browser compatibility
Chrome - 4
Firefox (Gecko) - 3.5
Internet Explorer - 8
Opera - 10.50
Safari (WebKit) - 4
See live example (credits to @cOlz)
https://codepen.io/gMohrin/pen/YZqgQW
$http({
method : 'GET',
url : $scope.BASEURL + 'file-download?fileType='+$scope.selectedFile,
responseType: 'arraybuffer',
headers : {
'Content-Type' : 'application/json'
}
}).success(function(data, status, headers, config) {
// TODO when WS success
var file = new Blob([ data ], {
type : 'application/json'
});
//trick to download store a file having its URL
var fileURL = URL.createObjectURL(file);
var a = document.createElement('a');
a.href = fileURL;
a.target = '_blank';
a.download = $scope.selectedFile+'.json';
document.body.appendChild(a);
a.click();
}).error(function(data, status, headers, config) {
});
In success part need to open local system, by which the user can choose, where to save file. Here I have used <a>. And I am hitting restful service
I want to save some numbers from a small program in a local JSON file.
Example:
const increaseButton = document.getElementById("increase-button")
const numberField = document.getElementById("count-field")
let myNum = 0
let myArray = []
increaseButton.addEventListener("click", increaseNum)
function increaseNum() {
myNum++
numberField.innerText = myNum
myArray.pop()
myArray.push(myNum)
let jsonString = JSON.stringify(Object.assign({}, myArray))
console.log(jsonString)
}
The jsonString should be saved in a local file "myjson.json".
Goal: If I increase the number with the increaseButton, the new value should be saved in the "myjson.json" file:
{
"numbers": {
"0":1}
}The only option I found was with node.js plugin "fs" and a lot of code. Couldn't it be easier?