reading data from file and displaying on browser - javascript

I am new to javascript (mostly work on backend) but now I want to create a visualization and want to use javascript for it.
I have data saved in a file in format
id1 uid1 rating
id1 uid2 rating2
Just to get started, I want to read data from this file and display it on my browser?
Do I need to start server.. or can i do it just like that.
Any suggestions/directions will be appreciated.
THanks

you need to learn about ajax,and deal with browser differences. A way that would work on firefox and chrome would be :
<body>
<div id="log"></div>
<script type="text/javascript">
var request = new XMLHttpRequest();//depends on the browser , several ways to create the object
request.onreadystatechange = function(e){
if(request.readyState == 4 && request.status==200){
// do whatever you need with the data
document.getElementById("log").innerText = request.responseText;
}
}
// assuming the file is called data and is located on current-path-on-server/data
request.open("GET","data",true);
request.send();
</script>
</body>
more about it :
https://developer.mozilla.org/en-US/docs/AJAX/Getting_Started

Related

Open local server file using plain javascript

I want to load locally stored data using plain javascript (no jquery for example) and then use it to display it in a table in html. My project structure looks like this:
root
- js
-- main.js
- res
-- data.csv
- index.html
I tried using a XMLHttpRequest, but somehow I get status 0 when trying to load the file and when printing the response text it prints out nothing at all.
The following method is called using window.onload:
var url = "file://../res/data.csv/";
varxmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (this.readyState === 4 && this.status === 200) {
console.log(this.responseText);
}
};
xmlhttp.open("GET", url, true);
xmlhttp.send();
I don't think you can access the file system through most browsers.
Even if it worked locally, it wouldn't work as soon as you put your page up on a server. This is because the client will be asking for a file that is local to itself, not the server.
Chrome may have something for you though:
https://www.html5rocks.com/en/tutorials/file/filesystem/

Javascript read and display content of a file

I want to read a file that's saved in the same folder. Then I want to show its content in a div in index.html. The problem: when I used require("fs") it didn't work since it wasn't running server-side. I have been looking around and can't find a simple answer. I want to make my website a little dynamic, so here is the code that should fire upon a button click:
function videos() {
var body = *read a file("insertfilename")*;
console.log(body);
document.getElementById("body").innerHTML = body;
}
"body" in this case is just the id I gave the div.
!EDIT!
Now to explain it further. I want to use it as my main website. When I go onto there it should open an empty html file, which has a scriptfile as source. "onload" it should read a file , which is also already on the server, and put its content into a div inside of the body. If I click on a hotlink or a Button, it should read another file and put that content into that div instead. Maybe that gives a little clarification on what I am trying to do. I dont want to reload to open other sites of mine.
Seems like you need some basic file fetching since you are not using a server. Have you tried FileReader for javascript? It is a very simple and straightforward object. The example on the page seems similar to what you are trying to accomplish, except you want to fetch the file, not the user.
You can use AJAX. It stands for Asynchronous JavaScript And XML. You can send asynchronous requests to server with it. Just make sure that file that you are requesting is on the same domain as JS file.
function videos() {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() { //this will execute when you receive response from the server
if (this.readyState == 4 && this.status == 200) {
document.getElementById("body").innerHTML = this.responseText;
console.log(this.responseText)
}
};
xhttp.open("GET", "filename.txt", true);
xhttp.send();
}
Here is W3schools tutorial if you want to learn more.

Request plain text file in javascript from URL?

I started a blog recently and coded it by hand. It is a static, CSS/HTML5 website. Upon sharing it with friends, I realized that when I would update it via FTP, it would be cached already by their browsers. I decided that I would keep all of my blog posts on new pages and then create a landing page that would somehow determine the newest post and forward users there after they clicked an enter button or something like that.
I was able to create a button that could forward them to a specific link, but I want to create a script that will always forward them to the newest page. So I created a file called 'getLatest.json' and uploaded it to an 'api' subfolder of my site. I then tried to use an XMLHttpRequest to load it:
function loadDoc() {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (xhttp.readyState == 4 && xhttp.status == 200) {
window.location = "http://latestBlogPost.com" +
xhttp.responseText.today;
//Today is a parent in the object returned.
}
};
xhttp.open("POST", "http://myWebsite.com/api/getLatest.json", true);
xhttp.send();
}
But that didn't work. The response was a null string. I tried using jquery to no avail.
I tried uploading a file called getLatest.html which contained the url in plaintext. That didn't work either.
tl;dr: Is there some way that I can get plaintext from a URL's html content?
edit: getLatest.json and getLatest.html contain a link to the newest blog post.
There are couple of ways to do this.
First your code is not working because you are using a "POST" it should be "GET", if you do that it will work.
Second easiest way is to create a java script file with variable declared and reference that file to your website
<script type="text/javascript" src="http://your javascript file"> </script>
This file contains your variable like this
var latestBlog = "http://....";
in your code use this variable. No more code required. but as i mentioned earlier if you change your HTTP Verb to get your code will work

marquee: fetch text from txt file hosted on cloud drive

I'm searching for an easy way to update a simple marquee on an HTML5 web page (e.g. displaying "we're on vacation from...") not via hard coding on the page itself but via an external txt file to be read. The thing is the text file should be hosted on a common cloud drive like Google drive or OneDrive. I make the file publicly available and include the public link to the txt file in the website code. Then I should be able to adapt the txt file in the cloud drive and see my edits in the marquee on the page.
Please support. Do you have other, better ideas? thx
<html>
<script type="text/javascript">
window.setInterval(function(){
ajaxCallFunction(); //calling every 5 seconds
}, 5000);
function ajaxCallFunction(){
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (xhttp.readyState == 4 && xhttp.status == 200) {
document.getElementById("textDisplay").innerHTML = xhttp.responseText;
}
};
xhttp.open("GET", "YOUR TEXT DOCUMENT HERE", true);
xhttp.setRequestHeader("Pragma","no-cache");
xhttp.setRequestHeader("Cache-Control","no-store, no-cache, must-revalidate, post-check=0, pre-check=0");
xhttp.setRequestHeader("Expires",0);
xhttp.setRequestHeader("Last-Modified", new Date(0));
xhttp.setRequestHeader("If-Modified-Since", new Date(0));
xhttp.send();
}
</script>
<marquee id="textDisplay"></marquee>
</html>
This will use ajax to pull the contents of your text file from wherever you have stored it, just use the share link from the cloud service you are using. It will update the text every 5 seconds.
EDIT
Ok, I've taken a look at your plunker and run the code in a browser. The error being returned in the console seems to indicate that the page you are requesting info from is redirecting you:
I'm not sure where to go from here, but I'll carry on looking none the less.

How to receive data from XMLHttpRequest in chome extension via javascript?

I wanna to send request form a webpage to chrome extension, and then in chrome extenison receive data and read data, is there any way to this?
Ex:
In doman www.nope.com/sendRequest.html will sent data to chrome extension via url chrome-extension://xxxxxxx/getData.htm?isToken=abc, and then extension will receive and can read data "isToken".
Here is my code in sendRequest.html
<script type="text/javascript">
function sendRequest() {
document.write("Sending request");
var req = new XMLHttpRequest();
req.open("POST", "chrome-extension://xxxxxxxxxx/getData.htm?isToken=abc", true);
req.onreadystatechange = function () {
if (req.readyState == 4) {
if (req.status == 200) {
alert(req.responseText);
document.write("OK");
}
}
};
req.send();
}
</script>
And in chrome extension file getData.htm, how can I get data?
(Edit: what type of data are you sending? Could you pass it through as a JSON encoded string, via GET? JSON.stringify() and JSON.parse() may be of use to you. :)
The following may be useful as a guide for accessing that POST/GET data. :) )
As far as I am aware, this is best done using some form of server side scripting. You could use window.location.search in JS, and split the string and perform the necessary functions, but I think server-side scripting may work best. :)
An example of a JS implementation could be as follows:
var url = window.location.search;
var params = url.substr(url.IndexOf("?") - 1, 30);
This would grab the parameters (starting at ? (inclusive), and continue for 30 chars. You could also use something like var params = url.substr(url.IndexOf("?") - 1, url.length); to get the whole parameters list.
How you use this from then on, is up to you, but you could pass it through a switch() or whatever you need. :)
Obviously, this being a chrome extension would limit your options regarding any server-side processing. :/
Edit: The above would go in getData.htm. :)

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