jquery实现图片上传前的预览

<div ></div>
<input  />

 

js代码

$("#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+")");
        
        }
 
    }
 
});