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How to read a local text file?

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北恋
北恋 2020-11-21 05:28

I’m trying to write a simple text file reader by creating a function that takes in the file’s path and converts each line of text into a char array, but it’s not working.

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  • 没有蜡笔的小新
    2020-11-21 05:42

    Local AJAX calls in Chrome are not supported due to same-origin-policy.

    Error message on chrome is like this: "Cross origin requests are not supported for protocol schemes: http, data, chrome, chrome-extension, https."

    This means that chrome creates a virtual disk for every domain to keep the files served by the domain using http/https protocols. Any access to files outside this virtual disk are restricted under same origin policy. AJAX requests and responses happen on http/https, therefore wont work for local files.

    Firefox does not put such restriction, therefore your code will work happily on the Firefox. However there are workarounds for chrome too : see here.

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  • 忘了有多久
    2020-11-21 05:43

    other example - my reader with FileReader class

    <html>
    <head>
        <link rel="stylesheet" href="http://code.jquery.com/ui/1.11.3/themes/smoothness/jquery-ui.css">
        <script src="http://code.jquery.com/jquery-1.10.2.js"></script>
        <script src="http://code.jquery.com/ui/1.11.3/jquery-ui.js"></script>
    </head>
    <body>
        <script>
            function PreviewText() {
            var oFReader = new FileReader();
            oFReader.readAsDataURL(document.getElementById("uploadText").files[0]);
            oFReader.onload = function (oFREvent) {
                document.getElementById("uploadTextValue").value = oFREvent.target.result; 
                document.getElementById("obj").data = oFREvent.target.result;
            };
        };
        jQuery(document).ready(function(){
            $('#viewSource').click(function ()
            {
                var text = $('#uploadTextValue').val();
                alert(text);
                //here ajax
            });
        });
        </script>
        <object width="100%" height="400" data="" id="obj"></object>
        <div>
            <input type="hidden" id="uploadTextValue" name="uploadTextValue" value="" />
            <input id="uploadText" style="width:120px" type="file" size="10"  onchange="PreviewText();" />
        </div>
        <a href="#" id="viewSource">Source file</a>
    </body>
</html>
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  • 离开以前
    2020-11-21 05:47

    In order to read a local file text through JavaScript using chrome, the chrome browser should run with the argument --allow-file-access-from-files to allow JavaScript to access local file, then you can read it using XmlHttpRequest like the following:

    var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function () {
   if (xmlhttp.readyState == 4) {
       var allText = xmlhttp.responseText;          
            }
        };
xmlhttp.open("GET", file, false);
xmlhttp.send(null);
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  • 情话喂你
    2020-11-21 05:49

    This might help, 

        var xmlhttp = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject("Microsoft.XMLHTTP");

    xmlhttp.onreadystatechange = function () {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
            alert(xmlhttp.responseText);
        }
    }

    xmlhttp.open("GET", "sample.txt", true);
    xmlhttp.send();
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  • 隐瞒了意图╮
    2020-11-21 05:50

    Using Fetch and async function

    const logFileText = async file => {
    const response = await fetch(file)
    const text = await response.text()
    console.log(text)
}

logFileText('file.txt')
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  • 梦如初夏
    2020-11-21 05:52 
    function readTextFile(file) {
    var rawFile = new XMLHttpRequest(); // XMLHttpRequest (often abbreviated as XHR) is a browser object accessible in JavaScript that provides data in XML, JSON, but also HTML format, or even a simple text using HTTP requests.
    rawFile.open("GET", file, false); // open with method GET the file with the link file ,  false (synchronous)
    rawFile.onreadystatechange = function ()
    {
        if(rawFile.readyState === 4) // readyState = 4: request finished and response is ready
        {
            if(rawFile.status === 200) // status 200: "OK"
            {
                var allText = rawFile.responseText; //  Returns the response data as a string
                console.log(allText); // display text on the console
            }
        }
    }
    rawFile.send(null); //Sends the request to the server Used for GET requests with param null
}

readTextFile("text.txt"); //<= Call function ===== don't need "file:///..." just the path

    - read file text from javascript
    - Console log text from file using javascript
    - Google chrome and mozilla firefox

    in my case i have this structure of files :

    the console.log result :

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