Home > Article > Web Front-end > JS implemented image preview plug-in and usage examples [no uploading images]

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

高洛峰Original: 2016-12-05 11:30:06895browse

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();
}

Statement：

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Previous article：Detailed explanation of WeChat JS-SDK custom sharing function examples [Share to friends/Share to Moments]Next article：Detailed explanation of WeChat JS-SDK custom sharing function examples [Share to friends/Share to Moments]

See more

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

Related articles