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JS implemented image preview plug-in and usage examples [no uploading images]

高洛峰Original: 2016-12-05 11:30:06972browse

The example in this article describes the JS implementation and usage of the image preview plug-in that does not require uploading. I share it with you for your reference, the details are as follows:

A few dozen lines of code, very awesome and very practical.

Supports the preview of multiple images, just new multiple objects.

html is as follows

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>uploadPreview演示</title>
  <script src="uploadPreview.js" type="text/javascript"></script>
  <script>
    window.onload = function () { 
      new uploadPreview({ UpBtn: "up_img", DivShow: "imgdiv", ImgShow: "imgShow" });
      new uploadPreview({ UpBtn: "up_img2", DivShow: "imgdiv2", ImgShow: "imgShow2" });
    }
  </script>
</head>
<body>
  <div id="imgdiv"><img  id="imgShow"    style="max-width:90%"/ alt="JS implemented image preview plug-in and usage examples [no uploading images]" ></div>
  <input type="file" id="up_img" />
  <div id="imgdiv"><img  id="imgShow2"    style="max-width:90%" / alt="JS implemented image preview plug-in and usage examples [no uploading images]" ></div>
  <input type="file" id="up_img2" />
</body>
</html>

plugin uploadPreview.js code is as follows

/*
*发布时间:2014年12月12日
*插件介绍:图片上传本地预览插件 兼容浏览器(IE 谷歌 火狐) 不支持safari 当然如果是使用这些内核的浏览器基本都兼容
*使用方法:
*界面构造(IMG标签外必须拥有DIV 而且必须给予DIV控件ID)
* <div id="imgdiv"><img  id="imgShow"    style="max-width:90%"  style="max-width:90%" / alt="JS implemented image preview plug-in and usage examples [no uploading images]" ></div>
* <input type="file" id="up_img" />
*调用代码:
* new uploadPreview({ UpBtn: "up_img", DivShow: "imgdiv", ImgShow: "imgShow" });
*参数说明:
*UpBtn:选择文件控件ID;
*DivShow:DIV控件ID;
*ImgShow:图片控件ID;
*Width:预览宽度;
*Height:预览高度;
*ImgType:支持文件类型 格式:["jpg","png"];
*callback:选择文件后回调方法;
*版本:v1.4
更新内容如下:
1.修复回调.
*版本:v1.3
更新内容如下:
1.修复多层级框架获取路径BUG.
2.去除对jquery插件的依赖.
*/
/*
*work:图片预览插件
*/
var uploadPreview = function(setting) {
  /*
  *work:this(当前对象)
  */
  var _self = this;
  /*
  *work:判断为null或者空值
  */
  _self.IsNull = function(value) {
    if (typeof (value) == "function") { return false; }
    if (value == undefined || value == null || value == "" || value.length == 0) {
      return true;
    }
    return false;
  }
  /*
  *work:默认配置
  */
  _self.DefautlSetting = {
    UpBtn: "",
    DivShow: "",
    ImgShow: "",
    Width: 100,
    Height: 100,
    ImgType: ["gif", "jpeg", "jpg", "bmp", "png"],
    ErrMsg: "选择文件错误,图片类型必须是(gif,jpeg,jpg,bmp,png)中的一种",
    callback: function() { }
  };
  /*
  *work:读取配置
  */
  _self.Setting = {
    UpBtn: _self.IsNull(setting.UpBtn) ? _self.DefautlSetting.UpBtn : setting.UpBtn,
    DivShow: _self.IsNull(setting.DivShow) ? _self.DefautlSetting.DivShow : setting.DivShow,
    ImgShow: _self.IsNull(setting.ImgShow) ? _self.DefautlSetting.ImgShow : setting.ImgShow,
    Width: _self.IsNull(setting.Width) ? _self.DefautlSetting.Width : setting.Width,
    Height: _self.IsNull(setting.Height) ? _self.DefautlSetting.Height : setting.Height,
    ImgType: _self.IsNull(setting.ImgType) ? _self.DefautlSetting.ImgType : setting.ImgType,
    ErrMsg: _self.IsNull(setting.ErrMsg) ? _self.DefautlSetting.ErrMsg : setting.ErrMsg,
    callback: _self.IsNull(setting.callback) ? _self.DefautlSetting.callback : setting.callback
  };
  /*
  *work:获取文本控件URL
  */
  _self.getObjectURL = function(file) {
    var url = null;
    if (window.createObjectURL != undefined) {
      url = window.createObjectURL(file);
    } else if (window.URL != undefined) {
      url = window.URL.createObjectURL(file);
    } else if (window.webkitURL != undefined) {
      url = window.webkitURL.createObjectURL(file);
    }
    return url;
  }
  /*
  *work:绑定事件
  */
  _self.Bind = function() {
    document.getElementById(_self.Setting.UpBtn).onchange = function() {
      if (this.value) {
        if (!RegExp("\.(" + _self.Setting.ImgType.join("|") + ")$", "i").test(this.value.toLowerCase())) {
          alert(_self.Setting.ErrMsg);
          this.value = "";
          return false;
        }
        if (navigator.userAgent.indexOf("MSIE") > -1) {
          try {
            document.getElementById(_self.Setting.ImgShow).src = _self.getObjectURL(this.files[0]);
          } catch (e) {
            var div = document.getElementById(_self.Setting.DivShow);
            this.select();
            top.parent.document.body.focus();
            var src = document.selection.createRange().text;
            document.selection.empty();
            document.getElementById(_self.Setting.ImgShow).style.display = "none";
            div.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
            div.style.width = _self.Setting.Width + "px";
            div.style.height = _self.Setting.Height + "px";
            div.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = src;
          }
        } else {
          document.getElementById(_self.Setting.ImgShow).src = _self.getObjectURL(this.files[0]);
        }
        _self.Setting.callback();
      }
    }
  }
  /*
  *work:执行绑定事件
  */
  _self.Bind();
}

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JS implemented image preview plug-in and usage examples [no uploading images]

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