使用jQuery在上传图片之前实现缩略图预览

$("#uploadImage").on("change", function(){      // Get a reference to the fileList      var files = !!this.files ? this.files : [];         // If no files were selected, or no FileReader support, return      if (!files.length || !window.FileReader) return;         // Only proceed if the selected file is an image      if (/^image/.test( files[0].type)){             // Create a new instance of the FileReader          var reader = new FileReader();             // Read the local file as a DataURL          reader.readAsDataURL(files[0]);             // When loaded, set image data as background of div          reader.onloadend = function(){             $("#uploadPreview").css("background-image", "url("+this.result+")");                    }         }     });