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问题:

I want to show contents of uploaded file in html, I can just upload a text file. My example.html:

<html xmlns="http://www.w3.org/1999/xhtml" >
<p>
Please specify a file, or a set of files:<br>
<input type="file" name="datafile" size="40">
</p>

<textarea id="2" name="y" style="width:400px;height:150px;"></textarea>
</html>

How can I show contents of any uploaded text file in textarea shown below?

回答1:

I've came here from google and was surprised to see no working example.

You can read files with FileReader API with good cross-browser support.

const reader = new FileReader()
reader.onload = event => console.log(event.target.result) // desired file content
reader.onerror = error => reject(error)
reader.readAsText(file) // you could also read images and other binaries

See fully working example below.

document.getElementById('input-file')
  .addEventListener('change', getFile)

function getFile(event) {
	const input = event.target
  if ('files' in input && input.files.length > 0) {
	  placeFileContent(
      document.getElementById('content-target'),
      input.files[0])
  }
}

function placeFileContent(target, file) {
	readFileContent(file).then(content => {
  	target.value = content
  }).catch(error => console.log(error))
}

function readFileContent(file) {
	const reader = new FileReader()
  return new Promise((resolve, reject) => {
    reader.onload = event => resolve(event.target.result)
    reader.onerror = error => reject(error)
    reader.readAsText(file)
  })
}

label {
  cursor: pointer;
}

textarea {
  width: 400px;
  height: 150px;
}

<div>
 <label for="input-file">Specify a file:</label><br>
 <input type="file" id="input-file">
</div>

<textarea id="content-target"></textarea>

回答2:

Here's one way:

HTML

<tr>
    <td>Select a File to Load:</td>
    <td><input type="file" id="fileToLoad"></td>
    <td><button onclick="loadFileAsText()">Load Selected File</button><td>
</tr>

JavaScript

function loadFileAsText(){
  var fileToLoad = document.getElementById("fileToLoad").files[0];

  var fileReader = new FileReader();
  fileReader.onload = function(fileLoadedEvent){
      var textFromFileLoaded = fileLoadedEvent.target.result;
      document.getElementById("inputTextToSave").value = textFromFileLoaded;
  };

  fileReader.readAsText(fileToLoad, "UTF-8");
}

回答3:

Try this.

HTML

<p>
Please specify a file, or a set of files:<br>
<input type="file" id="myFile" multiple size="50" onchange="myFunction()">
</p>

<textarea id="demo" style="width:400px;height:150px;"></textarea>

function myFunction(){
    var x = document.getElementById("myFile");
    var txt = "";
    if ('files' in x) {
        if (x.files.length == 0) {
            txt = "Select one or more files.";
        } else {
            for (var i = 0; i < x.files.length; i++) {
                txt += (i+1) + ". file";
                var file = x.files[i];
                if ('name' in file) {
                    txt += "name: " + file.name + "";
                }
                if ('size' in file) {
                    txt += "size: " + file.size + " bytes ";
                }
            }
        }
    } 
    else {
        if (x.value == "") {
            txt += "Select one or more files.";
        } else {
            txt += "The files property is not supported by your browser!";
            txt  += "The path of the selected file: " + x.value; // If the browser does not support the files property, it will return the path of the selected file instead. 
        }
    }
    document.getElementById("demo").innerHTML = txt;
}

Demo

回答4:

document.getElementById('input-file')
  .addEventListener('change', getFile)

function getFile(event) {
	const input = event.target
  if ('files' in input && input.files.length > 0) {
	  placeFileContent(
      document.getElementById('content-target'),
      input.files[0])
  }
}

function placeFileContent(target, file) {
	readFileContent(file).then(content => {
  	target.value = content
  }).catch(error => console.log(error))
}

function readFileContent(file) {
	const reader = new FileReader()
  return new Promise((resolve, reject) => {
    reader.onload = event => resolve(event.target.result)
    reader.onerror = error => reject(error)
    reader.readAsText(file)
  })
}

label {
  cursor: pointer;
}

textarea {
  width: 400px;
  height: 150px;
}

<div>
 <label for="input-file">Specify a file:</label><br>
 <input type="file" id="input-file">
</div>

<textarea id="content-target"></textarea>

Reading uploaded text file contents in html

问题:

回答1:

You can read files with FileReader API with good cross-browser support.

回答2:

回答3:

回答4:

收藏的人(0)

Reading uploaded text file contents in html

问题:

回答1:

You can read files with FileReader API with good cross-browser support.

回答2:

回答3:

回答4:

收藏的人(0)

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