I'm new to d3.js so I know this might seem as a silly question to some so please bear with me. I'm trying to parse a csv file which a user uploads and print it's output in the console. I'm able to parse the CSV file when I provide the absolute path of the CSV file but when I try doing the same with file upload functionality I'm not getting any output in the console..
Working Javascript Code..
var dataset = [];
d3.csv("sample.csv", function(data) {
dataset = data.map(function(d) { return [ d["Title"], d["Category"], d["ASIN/ISBN"], d["Item Total"] ]; });
console.log(dataset[0]);
console.log(dataset.length);
});
Console Output...
["Men's Brooks Ghost 8 Running Shoe Black/High Risk Red/Silver Size 11.5 M US", "Shoes", "B00QH1KYV6", "$120.00 "]
8
New HTML code..
<input type="file" id="csvfile" name="uploadCSV"/>
<br/>
<button onclick="howdy()">submit</button>
Modified Javascript Code(not working)..
var myfile = $("#csvfile").prop('files')[0];
var reader = new FileReader();
reader.onload = function(e) {
var text = reader.result;
}
reader.readAsDataURL(myfile);
var dataset = [];
d3.csv(reader.result , function(data) {
dataset = data.map(function(d) { return [ d["Title"], d["Category"], d["ASIN/ISBN"], d["Item Total"] ]; });
console.log(dataset[0]);
console.log(dataset.length);
})
Since there was no official documentation on how to handle user uploaded CSV file I can't figure out where I'm going wrong..Is there a way I can use HTML5 file reader?? Please help..
You are close but you don't need to and can't call d3.csv on a reader.result. d3.csv makes an async AJAX call to retrieve a CSV file from a server. You already have the file contents and just want to parse, so use d3.csv.parse.
Full working example:
<!DOCTYPE html>
<html>
<head>
<script data-require="d3#3.5.3" data-semver="3.5.3" src="//cdnjs.cloudflare.com/ajax/libs/d3/3.5.3/d3.js"></script>
</head>
<body>
<input type="file" onchange="loadFile()" />
<script>
var reader = new FileReader();
function loadFile() {
var file = document.querySelector('input[type=file]').files[0];
reader.addEventListener("load", parseFile, false);
if (file) {
reader.readAsText(file);
}
}
function parseFile(){
var doesColumnExist = false;
var data = d3.csv.parse(reader.result, function(d){
doesColumnExist = d.hasOwnProperty("someColumn");
return d;
});
console.log(doesColumnExist);
}
</script>
</body>
</html>
This is for d3-csv#3
<!-- https://www.jsdelivr.com/package/npm/d3-dsv -->
<script src="https://cdn.jsdelivr.net/npm/d3-dsv#3.0.1/dist/d3-dsv.min.js" integrity="sha256-IrzYc2a3nTkfvgAyowm/WKmIGdVCMCcccPtz+Y2y6VI=" crossorigin="anonymous"></script>
<input type="file" accept=".csv">
<button>test button</button>
<script>
const testData = `owner,repo,"branch name"
foo,demo,master
boo,"js awesome",sha1123456
`
document.querySelector(`input`).onchange = async e => {
const input = e.target
const file = input.files[0]
const reader = new FileReader()
reader.readAsText(new Blob(
[file],
{"type": file.type}
))
const fileContent = await new Promise(resolve => {
reader.onloadend = (event) => {
resolve(event.target.result)
}
})
const csvData = d3.csvParse(fileContent)
console.log(csvData)
}
document.querySelector(`button`).onclick = e => {
const csvData = d3.csvParse(testData)
console.log(csvData)
}
</script>
The below link may help you know the implementation of csvParse
csv.js : The csv, tsv(tab) are dependent by dsv.js
dsv.js
If you just load the CSV only then do not import the whole JS. (instead of the d3-csv.js)
https://cdn.jsdelivr.net/npm/d3#7.0.1/dist/d3.min.js
https://cdn.jsdelivr.net/npm/d3-dsv#3.0.1/dist/d3-dsv.min.js
This is an old question and I think we have to clarify some points.
How to load a local csv file
How to link the loaded file with D3
1. Load a file is very simple just check this example:
const fileInput = document.getElementById('csv')
const readFile = e => {
const reader = new FileReader()
reader.onload = () => {
document.getElementById('out').textContent = reader.result
}
reader.readAsBinaryString(fileInput.files[0])
}
fileInput.onchange = readFile
<div>
<p>Select local CSV File:</p>
<input id="csv" type="file" accept=".csv">
</div>
<pre id="out"><p>File contents will appear here</p></pre>
Here we have a simple input element with type="file" attribute, this lets us to pick a csv file. Then the readFile() function will be triggered whenever a file is selected and will call the onload function after reading the file as a binary string.
2. I recommend to use readAsDataURL() to integrate it with d3 like this:
const fileInput = document.getElementById('csv')
const previewCSVData = async dataurl => {
const d = await d3.csv(dataurl)
console.log(d)
}
const readFile = e => {
const file = fileInput.files[0]
const reader = new FileReader()
reader.onload = () => {
const dataUrl = reader.result;
previewCSVData(dataUrl)
}
reader.readAsDataURL(file)
}
fileInput.onchange = readFile
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"></script>
<div>
<p>Select local CSV File:</p>
<input id="csv" type="file" accept=".csv">
</div>
<pre id="out"><p>File contents will appear here</p></pre>
To integrate the loaded file we call previewCSVData() and pass the file then we parse it using d3.csv() method. Also lets use await because it is an asynchronous call.
Note:
d3.csv internally uses fetch and works for any type of URL, (httpURL, dataURL, blobURL, etc...)
Related
This question already has answers here:
Javascript read file without using input
(3 answers)
Closed 9 months ago.
I'm trying to load simple text file in javascript, unfortunately with no success.
my code is:
var my_text:any;
var my_file:File = new File([], "C:\\Users\\riki7\\Downloads\\classes.txt");
var reader = new FileReader();
reader.onload = function() {
my_text = reader.result;
};
reader.readAsText(my_file);
alert(my_text);
after this code runs, I would expect to see classes.txt file content in pop-up alert, instead I get 'undefined'.
my file contains a, b, c.
does anyone know what is my problem? maybe the first parameter for File() constructor?
You have to use html tag <input type="file" id="input" /> and then hung a event listener on it, like that
const inputElement = document.getElementById("input");
inputElement.addEventListener("change", handleFiles, false);
function handleFiles() {
const fileList = this.files; /* now you can work with the file list */
}
then after simply bypass your file into the FileReader
const reader = new FileReader();
reader.onload = (function(aImg) { return function(e) { aImg.src = e.target.result; }; })(img);
reader.readAsDataURL(file);
And i guess that would be it.
You can find more examples there: https://developer.mozilla.org/en-US/docs/Web/API/File_API/Using_files_from_web_applications
Having your code where your alert runs upfront the callback function. If you need to see alter with the content, simply move your alert into the callback function:
reader.onload = function() {
my_text = reader.result;
alert(my_text);
};
because my_text is not ready when you call alert outside.
<input type="file" id="selectedFile">
<p id="display"></p>
<script>
var fr = new FileReader();
let test;
document.getElementById('selectedFile').addEventListener('change', x);
function x() {
fr.onload = ()=>{
document.getElementById('display').innerText = fr.result;
test = fr.result;
alert(fr.result);
}
fr.readAsText(this.files[0]);
}
</script>
<html>
<head>
<script>
var fileReadEvent = function(event) {
var input = event.target;
var reader = new FileReader();
reader.onload = function(){
var text = reader.result;
alert(text)
};
};
</script>
</head>
<body>
<input type='file' accept='text/plain' onchange='fileReadEvent(event)'><br>
</body>
</html>
I have an image classifier that takes in images from the user and passes it to Tensorflow.js, but I can't seem to get the image loaded and passed to tf.browser.fromPixels.
I'm new to JavaScript and I'm not sure I'm implementing FileReader correctly.
<body>
<input id="image-selector" type="file">
<button id="predict-button">Predict</button>
<img id="selected-image" src=""/>
</body>
<script type="text/javascript">
document.getElementById("predict-button").onclick = async function() {run()};
async function run() {
let reader = new FileReader();
let dataURL = reader.result;
document.getElementById("selected-image").src=dataURL;
const image = tf.browser.fromPixels(selected-image);
const resized_image = tf.image.resizeBilinear(image, [300,300]).toFloat();
const batchedImage = resized_image.expandDims(0);
const MODEL_URL = 'web_model/model.json';
const model = await tf.loadGraphModel(MODEL_URL);
const result = model.predict(batchedImage);
result.print();
}
</script>
I'm currently learning JavaScript and I'm struggling to read a txt file and use its contents in the program, what I have so far:
fileBtn.addEventListener("change", function()
{
var content = [];
var file = fileBtn.files[0];
readFile(file, function(data)
{
console.log(JSON.parse(data));
//content.push(JSON.parse(data)) doesn't work, data is undef.
});
});
and a function readFile
function readFile(file, f)
{
var reader = new FileReader();
reader.onload = function(evt)
{
f(evt.target.result);
};
reader.readAsText(file);
}
My txt file is currenty only containing a "1", and it logs this number to the console but I can't work with it, if I try to push it into an array the values is suddenly undefined. My goal is to use the content of the file in the program later on
1 . no need to use JSON.parse if the text file only contain string .
data is containing all the text file content
2 . you need to put var content = [];
globally and not inside the function readFile
follow this snippet of code i think it will solve your problem
<html lang="en">
<head>
<meta charset="utf-8">
</head>
<body>
<label for="file-upload" class="custom-file-upload">
Custom Upload
</label>
<input id="file-upload" type="file" />
<input id="log-content" type="button" value="Click Me"/>
</body>
<script>
var content = [];
function readFile(file, f) {
var reader = new FileReader();
reader.onload = function (evt) {
f(evt.target.result);
};
var text = reader.readAsText(file);
}
var fileBtn = document.getElementById("file-upload");
var logContnt = document.getElementById("log-content");
logContnt.addEventListener("click", function () {
alert(content);
})
fileBtn.addEventListener("change", function () {
var file = fileBtn.files[0];
readFile(file, function (data) {
content.push(data);
});
});
</script>
</html>
I have an input tag:
<input type="file" id="fileUpload" accept=".csv"/>
that gets a csv file from the user. I then store the file into a variable as such:
const csvFile = document.getElementById('fileUpload');
How can I get the contents of the file into one big string if possible?
You can use the FileReader to read files.
<input type="file" id="fileUpload" accept=".csv" onchange="open(event)" />
<script>
var open = function(event) {
var input = event.target.files[0]
var readerObj = new FileReader()
readerObj.onload = function() {
var fileText = readerObj.result
//do something with fileText here....
}
readerObj.readAsText(input)
}
</script>
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?
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>
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.
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>
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'))
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>
FileReaderJS can read the files for you. You get the file content inside onLoad(e) event handler as e.target.result.