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How to open a file / browse dialog using javascript?

Posted by: admin November 30, 2017 Leave a comment

Questions:

Is there any way to open the browse for files dialog box when a <a href> link is clicked using javascript? It should function like a normal browse for files button and give the names/list of files selected in response.

Answers:

Here is a non-jQuery solution. Note you can’t just use .click() as some browsers do not support it.

<script type="text/javascript">
function performClick(elemId) {
   var elem = document.getElementById(elemId);
   if(elem && document.createEvent) {
      var evt = document.createEvent("MouseEvents");
      evt.initEvent("click", true, false);
      elem.dispatchEvent(evt);
   }
}
</script>
<a href="#" onclick="performClick('theFile');">Open file dialog</a>
<input type="file" id="theFile" />

Questions:
Answers:

Use this.

<script>
  function openFileOption()
{
  document.getElementById("file1").click();
}
</script>
     <input type="file" id="file1" style="display:none">
     <a href="#" onclick="openFileOption();return;">open File Dialog</a>

Questions:
Answers:

Here’s is a way of doing it without any Javascript and it’s also compatible with any browser.


EDIT: In Safari, the input gets disabled when hidden with display: none. A better approach would be to use position: fixed; top: -100em.


<label>
  Open file dialog
  <input type="file" style="position: fixed; top: -100em">
</label>

Also, if you prefer you can go the “correct way” by using for in the label pointing to the id of the input like this:

<label for="inputId">file dialog</label>
<input id="inputId" type="file" style="position: fixed; top: -100em">

Questions:
Answers:

Unfortunately, there isn’t a good way to browse for files with a JavaScript API. Fortunately, it’s easy to create a file input in JavaScript, bind an event handler to its change event, and simulate a user clicking on it. We can do this without modifications to the page itself:

$('<input type="file" multiple>').on('change', function () {
  console.log(this.files);
}).click();

this.files on the second line is an array that contains filename, timestamps, size, and type.

Questions:
Answers:

Create input element.

Missing from these answers is how to get a file dialog without a input element on the page.

The function to show the input file dialog.

function openFileDialog (accept, callback) {  // this function must be called from  a user
                                              // activation event (ie an onclick event)

    // Create an input element
    var inputElement = document.createElement("input");

    // Set its type to file
    inputElement.type = "file";

    // Set accept to the file types you want the user to select. 
    // Include both the file extension and the mime type
    inputElement.accept = accept;

    // set onchange event to call callback when user has selected file
    inputElement.addEventListener("change", callback)

    // dispatch a click event to open the file dialog
    inputElement.dispatchEvent(new MouseEvent("click")); 
}

NOTE the function must be part of a user activation such as a click event. Attempting to open the file dialog without user activation will fail.

NOTE input.accept is not used in Edge

Example.

Calling above function when user clicks an anchor element.

// wait for window to load
window.addEventListener("load", windowLoad);

// open a dialog function
function openFileDialog (accept, multy = false, callback) { 
    var inputElement = document.createElement("input");
    inputElement.type = "file";
    inputElement.accept = accept; // Note Edge does not support this attribute
    if (multy) {
        inputElement.multiple = multy;
    }
    if (typeof callback === "function") {
         inputElement.addEventListener("change", callback);
    }
    inputElement.dispatchEvent(new MouseEvent("click")); 
}

// onload event
function windowLoad () {
    // add user click event to userbutton
    userButton.addEventListener("click", openDialogClick);
}

// userButton click event
function openDialogClick () {
    // open file dialog for text files
    openFileDialog(".txt,text/plain", true, fileDialogChanged);
}

// file dialog onchange event handler
function fileDialogChanged (event) {
    [...this.files].forEach(file => {
        var div = document.createElement("div");
        div.className = "fileList common";
        div.textContent = file.name;
        userSelectedFiles.appendChild(div);
    });
}
.common {
    font-family: sans-serif;
    padding: 2px;
    margin : 2px;
    border-radius: 4px;
 }
.fileList {
    background: #229;
    color: white;
}
#userButton {
    background: #999;
    color: #000;
    width: 8em;
    text-align: center;
    cursor: pointer;
}

#userButton:hover {
   background : #4A4;
   color : white;
}
<a id = "userButton" class = "common" title = "Click to open file selection dialog">Open file dialog</a>
<div id = "userSelectedFiles" class = "common"></div>

Warning the above snippet is written in ES6.

Questions:
Answers:

you can’t use input.click() directly, but you can call this in other element click event.

var a = document.querySelector('a');
var inpupt = document.querySelector('a');
a.addEventListener('click', function (e) {
    input.click();
});

this tell you Using hidden file input elements using the click() method

Questions:
Answers:

I worked it around through this “hiding” div …

<div STYLE="position:absolute;display:none;"><INPUT type='file' id='file1' name='files[]'></div>

Questions:
Answers:

I know this is an old post, but another simple option is using the INPUT TYPE=”FILE” tag according to compatibility most major browser support this feature.