javascript - 上传前预览输入框架内的图像

Question

我在网上上传设计之前看到了一张预览图像并删除了，我一直在尝试这样做，但没有任何效果。我希望能够在输入元素框架内预览图像。像这样的事情:

抱歉，我的英语不太好。我尝试这样做

HTML 代码

<form>
<div class="row row-images">
  <label for="image">Images*</label>                   
  <div class="column image_container">
        <div class="post-image-collection">
        <label id="list">

        </label>
      <label class="post-image post-image-placeholder mrm mts empty">
        <input type="file" id="Photofile" name="images[]" required="required" multiple />
  <span class="icon-camera"><img src="https://cdn.onlinewebfonts.com/svg/img_134042.png"></span>
  <p class="uppercase">Photo</p>

</label>
</div>                        
      </div>
     </form>

CSS 代码

form .post-image-collection {
    margin: -20px 0px 0px -20px;
    overflow: hidden;
    }
    form .post-image {
    position: relative;
    float: left;
    height: 152px;
    width: 170px;
    background: #f2f2f2;
    border: 1px dashed #ccc;
    padding: 0;
    border-radius: 4px;
    text-align: center;
    cursor: pointer;
    }
    .mrm {
    margin-right: 20px;
    }
    .mts {
    margin-top: 10px;
    }
    form .post-image img {
    max-width: 80px;
    max-height: 80px;
    width: auto;
    height: auto;
    vertical-align: top;
    border-radius: 3px;
    overflow: hidden;
    }
    form .post-image .icon-camera {
    display: none;
    }
    form .post-image input {
    position: absolute;
    z-index: 2;
    opacity: 0;
    width: 100%;
    height: 100%;
    }
    form .post-image.empty {
    position: relative;
    float: left;
    height: 130px;
    width: 130px;
    background: #f2f2f2;
    border: 1px dashed #ccc;
    padding: 0;
    border-radius: 4px;
    text-align: center;
    cursor: pointer;
    vertical-align: top;
    }

    form .post-image.empty .icon-camera {
    display: block;
    height: 30px;
    line-height: 30px;
    left: 40%;
    position: absolute;
    text-align: center;
    top: 50%;
    width: 30px;
    cursor: inherit;
    margin: -15px 0px 0px -15px;
    }
    form .post-image.empty .icon-camera img {
    height: 60px;
    width: 60px;
    }
    form .post-image.empty input {
    cursor: pointer;
    }

    form .post-image p, .file_container-orange p {
    margin: 10px 0;
    margin: 1rem 0;
    text-align: center;
    font-family: "OpenSansSemiBold",sans-serif;
    }
    .uppercase {
    text-transform: uppercase;
    }
    #list{
    float: left;
    }
    .thumb {
    height: 130px;
    width: 130px;
    margin-right: 20px;
    margin-top: 10px;
    }
    .remove_img_preview {
    position: relative;
    top: -46px;
    right: 40px;
    font-size: 20px;
    line-height: 1;
    padding: 4px 6px;
    background: white;
    border-radius: 0px 0px 0px 3px;
    text-align:center;
    cursor:pointer;
    }
    .remove_img_preview:before {
    content: "×";
    }

Javascript代码

var count=0;
function handleFileSelect(evt) {
    var $fileUpload = $("input#Photofile[type='file']");
    count=count+parseInt($fileUpload.get(0).files.length);

    if (parseInt($fileUpload.get(0).files.length) > 4 || count>3) {
        alert("You can only upload a maximum of 3 photos");
        count=count-parseInt($fileUpload.get(0).files.length);
        evt.preventDefault();
        evt.stopPropagation();
        return false;
    }
    var files = evt.target.files;
    for (var i = 0, f; f = files[i]; i++) {
        if (!f.type.match('image.*')) {
            continue;
        }
        var reader = new FileReader();

        reader.onload = (function (theFile) {
            return function (e) {
                var span = document.createElement('span');
                span.innerHTML = ['<img class="thumb mrm mts" src="', e.target.result, '" title="', escape(theFile.name), '"/><span class="remove_img_preview"></span>'].join('');
                document.getElementById('list').insertBefore(span, null);
            };
        })(f);

        reader.readAsDataURL(f);
    }
}

$('#Photofile').change(function(evt){
    handleFileSelect(evt);
});  

$('#list').on('click', '.remove_img_preview',function () {
    $(this).parent('span').remove();

    //this is not working...
    var i = array.indexOf($(this));
    if(i != -1) {
        array.splice(i, 1);
    }
    // tried this too:
    //$(this).parent('span').splice( 1, 1 );

    count--;
});

请帮忙吗？

Answer 1

我已经修复了你的代码。在这里找到它:https://plnkr.co/edit/zjKMcigaZ3t6kLZv9aOc?p=preview 。另外，您不需要使用 javascript 检查上传的文件是否是图像。您可以使用 accept 属性阻止用户上传其他文件。像这样:

accept="image/*"

如果您有任何疑问，请告诉我。