get the data of uploaded file in javascript
JavascriptHtmlAjaxFile UploadJavascript Problem Overview
I want to upload a csv file and process the data inside that file. What is the best method to do so? I prefer not to use php script. I did the following steps. But this method only returns the file name instead of file path.So i didnt get the desired output.
<form id='importPfForm'>
<input type='file' name='datafile' size='20'>
<input type='button' value='IMPORT' onclick='importPortfolioFunction()'/>
</form>
function importPortfolioFunction( arg ) {
var f = document.getElementById( 'importPfForm' );
var fileName= f.datafile.value;
}
So how can i get the data inside that file?
Javascript Solutions
Solution 1 - Javascript
The example below is based on the html5rocks solution. It uses the browser's FileReader() function. Newer browsers only.
See http://www.html5rocks.com/en/tutorials/file/dndfiles/#toc-reading-files
In this example, the user selects an HTML file. It is displayed in the <textarea>.
<form enctype="multipart/form-data">
<input id="upload" type=file accept="text/html" name="files[]" size=30>
</form>
<textarea class="form-control" rows=35 cols=120 id="ms_word_filtered_html"></textarea>
<script>
function handleFileSelect(evt) {
let files = evt.target.files; // FileList object
// use the 1st file from the list
let f = files[0];
let reader = new FileReader();
// Closure to capture the file information.
reader.onload = (function(theFile) {
return function(e) {
jQuery( '#ms_word_filtered_html' ).val( e.target.result );
};
})(f);
// Read in the image file as a data URL.
reader.readAsText(f);
}
document.getElementById('upload').addEventListener('change', handleFileSelect, false);
</script>
Solution 2 - Javascript
you can use the new HTML 5 file api to read file contents
https://developer.mozilla.org/en-US/docs/Using_files_from_web_applications
but this won't work on every browser so you probably need a server side fallback.
Solution 3 - Javascript
The example below shows the basic usage of the FileReader to read the contents of an uploaded file. Here is a working Plunker of this example.
function init() {
document.getElementById('fileInput').addEventListener('change', handleFileSelect, false);
}
function handleFileSelect(event) {
const reader = new FileReader()
reader.onload = handleFileLoad;
reader.readAsText(event.target.files[0])
}
function handleFileLoad(event) {
console.log(event);
document.getElementById('fileContent').textContent = event.target.result;
}
<!DOCTYPE html>
<html>
<head>
<script src="script.js"></script>
</head>
<body onload="init()">
<input id="fileInput" type="file" name="file" />
<pre id="fileContent"></pre>
</body>
</html>
Solution 4 - Javascript
There exist some new tools on the blob itself that you can use to read the files content as a promise that makes you not have to use the legacy FileReader
// What you need to listen for on the file input
function fileInputChange (evt) {
for (let file of evt.target.files) {
read(file)
}
}
async function read(file) {
// Read the file as text
console.log(await file.text())
// Read the file as ArrayBuffer to handle binary data
console.log(new Uint8Array(await file.arrayBuffer()))
// Abuse response to read json data
console.log(await new Response(file).json())
// Read large data chunk by chunk
console.log(file.stream())
}
read(new File(['{"data": "abc"}'], 'sample.json'))
Solution 5 - Javascript
Try This
document.getElementById('myfile').addEventListener('change', function() {
var GetFile = new FileReader();
GetFile .onload=function(){
// DO Somthing
document.getElementById('output').value= GetFile.result;
}
GetFile.readAsText(this.files[0]);
})
<input type="file" id="myfile">
<textarea id="output" rows="4" cols="50"></textarea>
Solution 6 - Javascript
FileReaderJS can read the files for you. You get the file content inside onLoad(e) event handler as e.target.result.