Using the example code from the tutorial:
<html>
<head>
<script type="text/javascript"
src="dygraph-combined.js"></script>
</head>
<body>
<div id="graphdiv2"
style="width:500px; height:300px;"></div>
<script type="text/javascript">
g2 = new Dygraph(
document.getElementById("graphdiv2"),
"temperatures.csv", // path to CSV file
{} // options
);
</script>
</body>
</html>
I'd like to load only the last 10 lines from temperatures.csv instead of the whole file. Can I pass an instruction to the dygraphs' csv parser to do this?
There is no such option to set limit or/and offset according to source code https://github.com/danvk/dygraphs/blob/master/dygraph.js#L2942
But you can override function Dygraph.prototype.parseCSV_ in your code to achieve this.
For example like this:
// Save old function
var parseCSV_ = Dygraph.prototype.parseCSV_;
Dygraph.prototype.parseCSV_ = function(data) {
// Get all data
var ret = parseCSV_(data);
// Return only last 10 items
return ret.slice(ret.length - 10);
};
g2 = new Dygraph(
document.getElementById("graphdiv2"),
"temperatures.csv", // path to CSV file
{} // options
);
P.S. I'd recommend you to use new CSV file with only last 10 items to speed up loading, so generate it on back end if it is possible.
Related
I found a lot of good suggestions on how to load a csv/txt file into a html page into a table, but none of the solutions are working for me. Here is the code I am working with. I have both files located in my C: drive and basically would like to load this csv/txt file and show it on as a table in index.html. Thanks so much!
data.txt
heading1,heading2,heading3,heading4,heading5
value1_1,value2_1,value3_1,value4_1,value5_1
value1_2,value2_2,value3_2,value4_2,value5_2
index.html
<!DOCTYPE html>
<!-- saved from url=(0014)about:internet -->
<html lang="en">
<html>
<head>
<title>Test</title>
</head>
<body>
<script type="text/javascript">
$(document).ready(function() {
$.ajax({
type: "GET",
url: "data.txt",
dataType: "text",
success: function(data) {processData(data);}
});
});
function processData(allText) {
var allTextLines = allText.split(/\r\n|\n/);
var headers = allTextLines[0].split(',');
var lines = [];
for (var i=1; i<allTextLines.length; i++) {
var data = allTextLines[i].split(',');
if (data.length == headers.length) {
var tarr = [];
for (var j=0; j<headers.length; j++) {
tarr.push(headers[j]+":"+data[j]);
}
lines.push(tarr);
}
}
\\ alert(lines);
}
</script>
</body>
</html>
You can't access local files with JS. That would be serious security vulnerability, because you could send a malicious webpage to a user, which would download their files and send them to someone. As midrizi mentioned in the comments, you'll need a server to download files from there.
As others have noted, you can't automatically read a local file into the browser.
But you can prompt the user to select a file, using the <input type="file"> element.
Once a file has been selected via that input, it can be read via JavaScript.
<label for="file">Select a Text File:</label><br />
<input id="file" type="file" /><br/>
<button onclick="readFile()">Read File</button><br/>
let input = document.getElementById('file');
let contents = document.getElementById('contents');
function readFile () {
let file = input.files[0];
const reader = new FileReader();
reader.onload = function (evt) {
console.log('reader.onload');
contents.innerHTML = String(evt.target.result);
};
reader.readAsText(file);
}
If you can modify the data.txt a bit you can just load it as another script file without need for a server.
Change data.txt to this
var data = `heading1,heading2,heading3,heading4,heading5
value1_1,value2_1,value3_1,value4_1,value5_1
value1_2,value2_2,value3_2,value4_2,value5_2`
And load it as a javascript file before your actual script
<script type="text/javascript" src="data.txt"></script>
Then you can use the variable data which holds your file content without any ajax call.
There is no way you can retrieve a local file if you don't serve it, as pointed out in the comments to your question.
There are approaches you can take to that, though. If you can't serve it by any means, you could create a GitHub repo and upload your file there. Then you can use the link to your raw file:
And you can also take steps to automate that, but it should be easy enough committing your file locally whenever you update it and push it to GitHub. Just in case you're not familiar with Git and GitHub, here's a handy ref.
A word of caution: unless you have total control over the characters that you include in your CSV, parsing them by naively splitting commas like that might result in ugly stuff if the values within contain commas themselves. Some CSV files also come with extra stuff in the beginning of the file (like the sep indicator in the first row, which defines what character to interpret as separator). You may completely ignore these warnings if you're producing the CSV yourself.
Also I noticed your function does not take care of building the actual table, so I changed it so it does. I also used Fetch API to retrieve the data:
<!DOCTYPE html>
<!-- saved from url=(0014)about:internet -->
<html lang="en">
<html>
<head>
<title>Test</title>
</head>
<body>
<script type="text/javascript">
function processData(csv) {
let data = csv.split(/\r\n|\n/).map(v => v.split(','));
let headers = data.shift();
let table = document.createElement('table');
let thead = document.createElement('thead');
table.appendChild(thead);
thead.innerHTML = '<tr><th>' + headers.join('</th><th>') + '</th></tr>';
let tbody = document.createElement('tbody');
table.appendChild(tbody);
for (let row of data) {
tbody.innerHTML += '<tr><td>' + row.join('</td><td>') + '</td></tr>';
}
document.body.appendChild(table);
}
// I uploaded the CSV to a personal repo for this example,
// but you CAN use a local file as long as you *serve* it
fetch("https://raw.githubusercontent.com/gyohza/test/master/so/data.txt")
.then(res => res.text())
.then(text => processData(text));
</script>
</body>
</html>
I have some JavaScript code with Servlets code, I want to move all of them (between ) to external js file, but it doesn't work, what can I do? How to modify my code if only part of JavaScript can move to external file.
<script language="JavaScript" type="text/JavaScript">
var sel = document.getElementById('sel');
var selList = [];
<%
String key = "";
String text = "";
for(int i = 0; i < master.size(); i++) {
Map option = (Map) master.get(i);
key = (String) option.get("Code");
text = key + " " + (String) option.get("NAME");
%>
selList.push({
key: "<%=key%>",
text: "<%=text%>"
});
<%
}
%>
</script>
Here two options:
1-by not using ajax
external.js
var images;
function renderImages(){
//do things for showing images here.
//images variable has images data as JSON (i suggest you this way) so you can easily iterate over list and render it.
}
jsp
<html>
<head>
<script type="text/javascript" src="external.js"></script>
<script>
images = "<%=request.getAttribute("imageDataAsJSON")%>"; //here i assume you populate request variable with your image data in JSON format. Be careful about parse errors due to ' and ".
</script>
</head>
<body>
<script>
renderImages();
</script>
</body>
</html>
2-by using ajax (you can seperate client side logic into external js code and populate data into it by doing ajax calls to server side.)
external.js
function renderImages(){
//do ajax to your servlet which returns image data as JSON.
//iterate over image data and render your html elements accordingly.
}
jsp
<html>
<head>
<script type="text/javascript" src="external.js"></script>
</head>
<body>
</body>
</html>
I have an XLS file with data in it.
The excel file has a lot of reference in one column, so I want the user to type the reference then the web page search for the reference and show the data in the line found.
I can't use a server, so I want to do it without PHP or things like that.
Is it possible ? How can I do that ?
Thanks
Here is the sample of js-xlsx, and will return all values in all worksheets as JSON object, you may need to modify by your usage.
<html>
<script src="xlsx.core.min.js"></script>
<head></head>
<body>
</body>
<script type ="text/javascript">
"use strict";
var X = XLSX;
function convertFile(b64data) {
var wb = X.read(b64data, {type: 'base64',WTF: false});
var result = {};
wb.SheetNames.forEach(function(sheetName) {
var roa = X.utils.sheet_to_row_object_array(wb.Sheets[sheetName]);
if(roa.length > 0){
result[sheetName] = roa;
}
});
return JSON.stringify(result, 2, 2);
}
</script>
</html>
More option (by upload file, drag and drop option), you can study the source code of js-xlsx example: http://oss.sheetjs.com/js-xlsx/
You don't need PHP but at least Javascript.
You can do it like this:
var excel = new ActiveXObject("Excel.Application");
var wb = excel.Workbooks.Open("Path/to/your/excel/file.xls");
var ws = wb.ActiveSheet;
var cell = ws.Cells.Find("your search input");
alert(cell.Row);
excel.Quit();
I hope i could help you;)
I am trying to learn web programming and Javascript.
I'm trying to take whatever the user copied from an Excel spreadsheet and create a JavaScript spreadsheet/table that includes dropdowns out of it.
So basically the user would paste the input into a blank field, press the submit button, and JavaScript would generate an Excel-like spreadsheet which would have the data sorted accordingly. The dropdowns would be at the top of each column and allow the user to select either ready/not ready. This is being designed for a confluence WIKI page.
This is what I have so far, right now the code parses the input-field and creates a multi-dimensional array. After that, the array will be logged on the console. I need help getting everything displayed on the wiki page.
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
</head>
<body>
<textarea id="textarea"></textarea>
<button id="loadPaste">parse</button>
<script type="text/javascript">
var excel = new Array();
$(document).ready(function() {
$('#loadPaste').click(function() {
var text = $('#textarea').val();
var rows = text.split("\n");
for (var i = 0; i < rows.length; i++) {
excel[i] = rows[i].split("\t");
}
console.log(excel);
});
});
</script>
</body>
</html>
Lets close this one: //THIS IS #Downgoat response with little explanation about xml parser.
use an xml parser var xml = (new DOMParser()).parseFromString($('#textarea').val(), 'text/xml')
var text, parser, xmlDoc;
text = "<bookstore><book>" +
"<title>Everyday Italian</title>" +
"<author>Giada De Laurentiis</author>" +
"<year>2005</year>" +
"</book></bookstore>";
parser = new DOMParser();
xmlDoc = parser.parseFromString(text,"text/xml");
document.getElementById("demo").innerHTML =
xmlDoc.getElementsByTagName("title")[0].childNodes[0].nodeValue;
<html>
<body>
<p id="demo"></p>
</body>
</html>
I uploaded the following index.html file for a subdomain and it isn't properly loading. It only shows the title tag.
I want it to load when I go to xxx.myapp.com. The setup is ok on godaddy because I see the title, but the rest of the page doesn't render. Also I see the network requests on the server bit nothing...
Any thoughts?
<!DOCTYPE html>
<html>
<head>
<title>MI Testing title</title>
<!--Load the AJAX API-->
<script type="text/javascript" src="https://www.google.com/jsapi"></script>
<script type="text/javascript" src="http://www.myapp.com/JS/HelperFunctions.js"></script>
<script type="text/javascript" src="http://www.myapp.com/JS/Settings.js"></script>
<!-- zurb foundation-->
<link type="text/css" rel="stylesheet" href="http://www.myapp.com/foundation-4.3.1/CSS/foundation.css" />
<link type="text/css" rel="stylesheet" href="http://www.myapp.com/foundation-4.3.1/CSS/foundation.min.css" />
<link type="text/css" rel="stylesheet" href="http://www.myapp.com/foundation-4.3.1/CSS/normalize.css" />
<!--Local css -->
<link type="text/css" rel="stylesheet" href="http://www.myapp.com/CSS/AnalyticsIndex.css"/>
<script src="http://code.jquery.com/jquery-latest.min.js"></script>
<script type="text/javascript">
// Load the Visualization API and the piechart package.
google.load('visualization', '1.0', {'packages':['corechart']});
// Set a callback to run when the Google Visualization API is loaded.
google.setOnLoadCallback(drawCharts);
/*
Called when library loaded
*/
function drawCharts(){
drawDailyAverageSessionLength();
drawUsersGender();
}
/*
Draws the chart for average session length by day
*/
function drawDailyAverageSessionLength() {
//Apit to get the data from
var api = GET_AVG_SESSIONS_URL+"2013/0/0";
//Request data (using jquery/ajax)
$.getJSON(api,function(data){
//Start a days and seconds array
var days = [];
var seconds = [];
//Init google data array
var googData = new google.visualization.DataTable();
//Add X Y columns
googData.addColumn('string', 'days');
googData.addColumn('number', 'seconds');
//Init sort array
var sorted =[];
//Parse the results to get the dates
for (var key in data){
var date = new Date(key);
sorted.push(date);
}
//Sort the array
sorted.sort(sortDateArrayDescending);
//Split results
for (i=0;i<sorted.length;i++){
//Get the date object
var day = sorted[i];
//Add 1 to month
var month = day.getMonth()+1;
//Parse to string
var newKey = day.getFullYear()+'-'+month+'-'+day.getDate();
var short = month+'/'+day.getDate();
//Add date to days array
days.push(short);
//Add to integer array
seconds.push(parseInt(data[newKey]));
}
//Parse to google data
for (i=0; i<days.length;i++){
googData.addRow([days[i], seconds[i]]);
}
// Set chart options
var options = {'title':'Average session length (NOT ACCURATE since end of sessions aren\'t being tracked)',
'width':1200,
'height':400};
// Instantiate and draw our chart, passing in some options.
var chart = new google.visualization.LineChart(document.getElementById('averageSessionLengthChart'));
chart.draw(googData, options);
});
}
/*
Draws the chart for average session length by day
*/
function drawUsersGender() {
//Apit to get the data from
var api = GET_USERS_SEX;
//Request data (using jquery/ajax)
$.getJSON(api,function(data){
//Start a days and seconds array
var result = [['gender', 'number']];
//Iterate over the genders
for (var gender in data){
//Get the value pair and push
var entry = [gender, parseInt(data[gender])];
result.push(entry);
}
//Parse to google data
var data = google.visualization.arrayToDataTable(result);
//Display options
var options = {
title:'Gender for registered users',
'width':600,
'height':400
};
//Draw the chart
var chart = new google.visualization.PieChart(document.getElementById('genderChart'));
chart.draw(data, options);
});
}
</script>
</head>
<body>
<div class="row">
<div id = "averageSessionLengthChart" class="large-12 small-12 columns">
</div>
</div>
<div class="row">
<div id = "genderChart" class="large-12 small-12 columns">
</div>
</div>
</body>
</html>
Try a developper console from a PC outside your network to see what requests are sent (Press 'F12' on chrome or install the firebug extension on Firefox).
There should be a "Network" tab that shows what requests are made from the page.
Maybe it will help you understand what is happening.