Rails + javascript - 上传前的图片预览 [英] Rails+javascript - image preview before upload

问题描述

我想在上传之前显示图片预览，因为我使用下面给出的代码。

I want to show an image preview before upload, for that I am using the code given below.

它适用于firefox，但不适用于IE8

It works with firefox, but doesn't work with IE8

<%= image_tag @image, :id=>"preview-photo" %>
<%= file_field 'image','photo', :onchange => "preview(this);" %>

function preview(this) {
  document.getElementById("preview-photo").src = this.value;
  return;
}

是否有任何解决方案可以在IE8和其他浏览器中预览图像？

Is there any solution to preview the image in IE8 and other browsers?

推荐答案

在ERB中：获取输入，并为其指定一个类名和动态ID，并使用dyanamic id创建一个图像标记将显示预览图片。

In ERB: Take input, and give it a class name and dynamic id, and also make a image tag with dyanamic id where you will show the preview pic.

<%= f.file_field :photo, :class => 'photo_upload', :id => "image_#{image.id}" %>  
<%= image_tag("preview.png", :id => "image_#{image.id}_medium") %>

在JAVASCRIPT中：

In JAVASCRIPT:

function readURL(input) {
    if (input.files && input.files[0]) {
        var reader = new FileReader();            
      reader.onload = function (e) {
          $(document.getElementById(input.id + "_medium")).attr('src', e.target.result);
        }

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

$(".photo_upload").change(function(){
    readURL(this);
});

这篇关于Rails + javascript - 上传前的图片预览的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！