JS FileReader: Read CSV from local file and jquery-csv
I have a CSV file in the same directory as the html page and I would like to use a FileReader to read the contents of the file into the jquery-csv To Arrays function, but I cannot get it to work as expected. I think I understand the asynchronous nature of this task, but have I portrayed it correctly? Here I am trying to output the second cell to the second column. Thanks for any help.
<script type="text/javascript" src="https://www.google.com/jsapi?autoload={'modules':[{'name':'visualization','version':'1','packages':['timeline']}]}"></script>
<script src="https://code.jquery.com/jquery-1.9.1.min.js"></script>
<script src="jquery.csv-0.71.js"></script>
<script type="text/javascript">
var reader = new FileReader();
reader.onload = function(e) {
var text = e.target.result;
var data = $.csv.toArrays(text);
document.write(data[1][1]);
}
reader.readAsText('data.csv');
</script>
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2 answers
It won't work. You do not have permission to read files with javascript from your browser. The only way to handle this is to create an input tag [type = file] and add an OnChange event to it. For example:
document.getElementById('fileupload').addEventListener('change', function (e) {
var files = e.target.files;
//proceed your files here
reader.readAsText(files[0]);
}, false);
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Here's a working demo provided by jquery-csv
<html>
<head>
<meta charset="utf-8" />
<title>Demo - CSV-to-Table</title>
</head>
<body>
<div id="inputs" class="clearfix">
<input type="file" id="files" name="files[]" multiple />
</div>
<hr />
<output id="list">
</output>
<hr />
<table id="contents" style="width:100%; height:400px;" border>
</table>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script>
<script src="http://evanplaice.github.io/jquery-csv/src/jquery.csv.min.js"></script>
<script>
$(document).ready(function() {
if(isAPIAvailable()) {
$('#files').bind('change', handleFileSelect);
}
});
function isAPIAvailable() {
// Check for the various File API support.
if (window.File && window.FileReader && window.FileList && window.Blob) {
// Great success! All the File APIs are supported.
return true;
} else {
// source: File API availability - http://caniuse.com/#feat=fileapi
// source: <output> availability - http://html5doctor.com/the-output-element/
document.writeln('The HTML5 APIs used in this form are only available in the following browsers:<br />');
// 6.0 File API & 13.0 <output>
document.writeln(' - Google Chrome: 13.0 or later<br />');
// 3.6 File API & 6.0 <output>
document.writeln(' - Mozilla Firefox: 6.0 or later<br />');
// 10.0 File API & 10.0 <output>
document.writeln(' - Internet Explorer: Not supported (partial support expected in 10.0)<br />');
// ? File API & 5.1 <output>
document.writeln(' - Safari: Not supported<br />');
// ? File API & 9.2 <output>
document.writeln(' - Opera: Not supported');
return false;
}
}
function handleFileSelect(evt) {
var files = evt.target.files; // FileList object
var file = files[0];
// read the file metadata
var output = ''
output += '<span style="font-weight:bold;">' + escape(file.name) + '</span><br />\n';
output += ' - FileType: ' + (file.type || 'n/a') + '<br />\n';
output += ' - FileSize: ' + file.size + ' bytes<br />\n';
output += ' - LastModified: ' + (file.lastModifiedDate ? file.lastModifiedDate.toLocaleDateString() : 'n/a') + '<br />\n';
// read the file contents
printTable(file);
// post the results
$('#list').append(output);
}
function printTable(file) {
var reader = new FileReader();
reader.readAsText(file);
reader.onload = function(event){
var csv = event.target.result;
var data = $.csv.toArrays(csv);
var html = '';
for(var row in data) {
html += '<tr>\r\n';
for(var item in data[row]) {
html += '<td>' + data[row][item] + '</td>\r\n';
}
html += '</tr>\r\n';
}
$('#contents').html(html);
};
reader.onerror = function(){ alert('Unable to read ' + file.fileName); };
}
</script>
</body>
</html>
Disclaimer: I am the author of jquery-csv
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