Comment prévisualiser plusieurs images avant de les télécharger ?

Question

J'ai une page contenant quatre images que l'utilisateur peut sélectionner. Je veux que l'utilisateur puisse avoir un aperçu de chaque image sur le site avant de la télécharger.

Le code JavaScript ci-dessous ne fonctionne que pour une seule image, mais j'aimerais qu'il fonctionne pour plusieurs images téléchargées par l'intermédiaire de l'application <input type="file"> .

Quelle sera la meilleure façon de procéder ?

function readURL(input) {
    if (input.files && input.files[0]) {
        var reader = new FileReader();

        reader.onload = function (e) {
            $('#output').attr('src', e.target.result);
        }

        reader.readAsDataURL(input.files[0]);
    }
}

$("#file-input").change(function () {
    readURL(this);
});

Answer 1

$(function() {
    // Multiple images preview in browser
    var imagesPreview = function(input, placeToInsertImagePreview) {

        if (input.files) {
            var filesAmount = input.files.length;

            for (i = 0; i < filesAmount; i++) {
                var reader = new FileReader();

                reader.onload = function(event) {
                    $($.parseHTML('<img>')).attr('src', event.target.result).appendTo(placeToInsertImagePreview);
                }

                reader.readAsDataURL(input.files[i]);
            }
        }

    };

    $('#gallery-photo-add').on('change', function() {
        imagesPreview(this, 'div.gallery');
    });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<input type="file" multiple id="gallery-photo-add">
<div class="gallery"></div>

function previewImages() {

  var preview = document.querySelector('#preview');

  if (this.files) {
    [].forEach.call(this.files, readAndPreview);
  }

  function readAndPreview(file) {

    // Make sure `file.name` matches our extensions criteria
    if (!/\.(jpe?g|png|gif)$/i.test(file.name)) {
      return alert(file.name + " is not an image");
    } // else...

    var reader = new FileReader();

    reader.addEventListener("load", function() {
      var image = new Image();
      image.height = 100;
      image.title  = file.name;
      image.src    = this.result;
      preview.appendChild(image);
    });

    reader.readAsDataURL(file);

  }

}

document.querySelector('#file-input').addEventListener("change", previewImages);

<input id="file-input" type="file" multiple>
<div id="preview"></div>

Answer 2

<script type="text/javascript">

var upcontrol = {
  queue : null, // upload queue
  now : 0, // current file being uploaded
  start : function (files) {
  // upcontrol.start() : start upload queue

    // WILL ONLY START IF NO EXISTING UPLOAD QUEUE
    if (upcontrol.queue==null) {
      // VISUAL - DISABLE UPLOAD UNTIL DONE
      upcontrol.queue = files;
      document.getElementById('uploader').classList.add('disabled');
      // PREVIEW UPLOAD IMAGES
       upcontrol.preview();*enter code here*
      //PROCESS UPLOAD ON CLICK 

    $('#add_files').on('click', function() {
       upcontrol.run();
    });
    }
  },
  preview : function() {
    //upcontrol.preview() : preview uploading file
        if (upcontrol.queue) {
            var filesAmount = upcontrol.queue.length;

            for (i = 0; i < filesAmount; i++) {
                var reader = new FileReader();

                reader.onload = function(event) {
                  var fimg = document.createElement('img') 
                    fimg.src =  event.target.result,
                      fimg.classList = "col-sm-6 col-md-6 col-lg-4 float-left center",
                      document.getElementById('gallery').appendChild(fimg);                
                }
                reader.readAsDataURL(upcontrol.queue[i]);
            }
        }
    },
  run : function () {
  // upcontrol.run() : proceed upload file

    var xhr = new XMLHttpRequest(),
        data = new FormData();
    data.append('file-upload', upcontrol.queue[upcontrol.now]);
    xhr.open('POST', './lockeroom/func/simple-upload.php', true);
    xhr.onload = function (e) {

      // SHOW UPLOAD STATUS
      var fstat = document.createElement('div'),

          txt = upcontrol.queue[upcontrol.now].name + " - ";
      if (xhr.readyState === 4) {
        if (xhr.status === 200) {
          // SERVER RESPONSE
          txt += xhr.responseText;
        } else {
          // ERROR
          txt += xhr.statusText;
        }
      }
      fstat.innerHTML = txt;
      document.getElementById('upstat').appendChild(fstat);

      // UPLOAD NEXT FILE
      upcontrol.now++;
      if (upcontrol.now < upcontrol.queue.length) {
        upcontrol.run();
      }
      // ALL DONE
      else {
        upcontrol.now = 0;
        upcontrol.queue = null;
        document.getElementById('uploader').classList.remove('disabled');
      }
    };
    xhr.send(data);
  }
};

window.addEventListener("load", function () {
  // IF DRAG-DROP UPLOAD SUPPORTED
  if (window.File && window.FileReader && window.FileList && window.Blob) {
    /* [THE ELEMENTS] */
    var uploader = document.getElementById('uploader');

    /* [VISUAL - HIGHLIGHT DROP ZONE ON HOVER] */
    uploader.addEventListener("dragenter", function (e) {
      e.preventDefault();
      e.stopPropagation();
      uploader.classList.add('highlight');
    });
    uploader.addEventListener("dragleave", function (e) {
      e.preventDefault();
      e.stopPropagation();
      uploader.classList.remove('highlight');
    });

    /* [UPLOAD MECHANICS] */
    // STOP THE DEFAULT BROWSER ACTION FROM OPENING THE FILE
    uploader.addEventListener("dragover", function (e) {
      e.preventDefault();
      e.stopPropagation();
    });

    // ADD OUR OWN UPLOAD ACTION
    uploader.addEventListener("drop", function (e) {
      e.preventDefault();
      e.stopPropagation();
      uploader.classList.remove('highlight');
      upcontrol.start(e.dataTransfer.files);
    });
  }
  // FALLBACK - HIDE DROP ZONE IF DRAG-DROP UPLOAD NOT SUPPORTED
  else {
    document.getElementById('uploader').style.display = "none";
  }
});
</script>

j'ai utilisé quelque chose comme ça et j'ai obtenu le meilleur résultat et facile à comprendre.

Answer 3

function appendRows(){
    $i++;
    var html='';
    html+='<div id="remove'+$i+'"><input type="file" name="imagefile[]" accept="image/*" onchange="appendloadFile('+$i+')"><img id="outputshow'+$i+'" height="70px" width="90px"><i onclick="deleteRows('+$i+')" class="fas fa-trash-alt"></i></div>';
     $("#appendshow").append(html);
}

function appendloadFile(i){
    var appendoutput = document.getElementById('outputshow'+i+'');
    appendoutput.src = URL.createObjectURL(event.target.files[0]);
}

Answer 4

https://stackoverflow.com/a/59985954/8784402

Voie ES2017

// convert file to a base64 url
const readURL = file => {
    return new Promise((res, rej) => {
        const reader = new FileReader();
        reader.onload = e => res(e.target.result);
        reader.onerror = e => rej(e);
        reader.readAsDataURL(file);
    });
};

// for demo
const fileInput = document.createElement('input');
fileInput.type = 'file';
const img = document.createElement('img');
img.attributeStyleMap.set('max-width', '320px');
document.body.appendChild(fileInput);
document.body.appendChild(img);

const preview = async event => {
    const file = event.target.files[0];
    const url = await readURL(file);
    img.src = url;
};

fileInput.addEventListener('change', preview);

Answer 5

$(function() {
    // Multiple images preview in browser
    var imagesPreview = function(input, placeToInsertImagePreview) {

        if (input.files) {
            var filesAmount = input.files.length;

            for (i = 0; i < filesAmount; i++) {
                var reader = new FileReader();

                reader.onload = function(event) {
                    $($.parseHTML('<img>')).attr('src', event.target.result).appendTo(placeToInsertImagePreview);
                }

                reader.readAsDataURL(input.files[i]);
            }
        }

    };

    $('#gallery-photo-add').on('change', function() {
        imagesPreview(this, 'div.gallery');
    });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<input type="file" multiple id="gallery-photo-add">
<div class="gallery">

$(function() {
    // Multiple images preview in browser
    var imagesPreview = function(input, placeToInsertImagePreview) {

        if (input.files) {
            var filesAmount = input.files.length;

            for (i = 0; i < filesAmount; i++) {
                var reader = new FileReader();

                reader.onload = function(event) {
                    $($.parseHTML('<img>')).attr('src', event.target.result).appendTo(placeToInsertImagePreview);
                }

                reader.readAsDataURL(input.files[i]);
            }
        }

    };

    $('#gallery-photo-add').on('change', function() {
        imagesPreview(this, 'div.gallery');
    });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<input type="file" multiple id="gallery-photo-add">
<div class="gallery">