CODEWITHSUNDEEP
javascripthtml
fGk
fGk

Reputation: 51

How to read a text file saved on my computer using javascript

I have a text file that is being updated regularly and I want to know if it is possible to read the file, line by line, with javascript and save the values in variables and then update the html page with the new values every time the page is loaded. The html page is a simple page to display information at work, not a live web page, and does not require any user input other than just navigating between the two pages. The text file is on a network drive that everyone has access to. Here is an example of what I'm trying to accomplish: 

var value1;
var value2;

Read the file with javascript if possible and extract data and assign to value1 and value2.

document.getElementsByClassName("class for <p>")[0].innerHTML = value;
document.getElementsByClassName("class for another <p>")[0].innerHTML = value;

I have googled this but was not able to find anything that worked. If this is not possible with JS, any suggestions on how this can be done differently. Thanks in advance.

Upvotes: 5

Views: 13445

Answers (2)

Nitheesh
Nitheesh

Reputation: 20016

You could use the javascript FileReader and input type="file" to read the local files in your machine. Please see the below attached code for example.

<!DOCTYPE html>
<html>

<head>
    <script>
        function OnFileLoad() {
            var file = document.getElementById("FileReader").files[0];
            var textType = /text.*/;
            var fileDisplayArea = document.getElementById("FileContent");
            if (file.type.match(textType)) {
                var reader = new FileReader();

                reader.onload = function (e) {
                    fileDisplayArea.innerText = reader.result;
                }

                reader.readAsText(file);
            } else {
                fileDisplayArea.innerText = "File not supported!"
            }
        }
    </script>
</head>

<body>
    <input type="file" id="FileReader" onchange="OnFileLoad()" />
    <div id="FileContent">Your content will appear here</div>
</body>

</html>

In order to specify the file path you might need to have a server as well. I have attached a sample code here with. You can find the details regarding Specifying the file path here and issues that will happen to read file without a server here

<!DOCTYPE html>
<html>

<head>
    <script>
        function readTextFile(file) {
            var rawFile = new XMLHttpRequest();
            rawFile.open("GET", file, false);
            var fileDisplayArea = document.getElementById("FileContent");
            rawFile.onreadystatechange = function () {
                if (rawFile.readyState === 4) {
                    if (rawFile.status === 200 || rawFile.status == 0) {
                        var allText = rawFile.responseText;
                        fileDisplayArea.innerText = allText;
                    }
                } else {
                    fileDisplayArea.innerText = "File not supported!"
                }
            }
            rawFile.send(null);
        }
        readTextFile("file:///C:/Users/t0423/Desktop/test.js")
    </script>
</head>

<body>
    <div id="FileContent">Your content will appear here</div>
</body>

</html>

Upvotes: 1

acrazing
acrazing

Reputation: 2284

At first, you need to use a input[type=file] to get a File.

<input type=file id=file/>
<div id=result></div>

And then use FileReader to read file to target format, just like base64, text, buffer.

const file = document.getElementById('file').files[0]
const result = document.getElementById('result')
const reader = new FileReader
reader.addEventListener('load', () => {
    result.innerHTML = reader.result
})
reader.readAsText(file, 'UTF-8')

See: https://developer.mozilla.org/en-US/docs/Web/API/FileReader

Upvotes: 6

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