File API - FileReader (readAsDataURL)

by Ufuk Ozdemir

HTML

<!DOCTYPE html>
<html>
<head>
    <title>File API - FileReader as Data URL</title>
</head>
<body>
    <header>
        <h1>File API - FileReader</h1>
    </header>
    <article>
        <label for="files">Select multiple files: </label>
        <input id="files" type="file" multiple/>
        <output id="result" />
    </article>
</body>
</html>

CSS

body{
    font-family: 'Segoe UI';
    font-size: 12pt;
}

header h1{
    font-size:12pt;
    color: #fff;
    background-color: #1BA1E2;
    padding: 20px;

}
article
{
    width: 80%;
    margin:auto;
    margin-top:10px;
}


.thumbnail{

    height: 100px;
    margin: 10px;    
}

JavaScript

window.onload = function(){
        
    //Check File API support
    if(window.File && window.FileList && window.FileReader)
    {
        var filesInput = document.getElementById("files");
        
        filesInput.addEventListener("change", function(event){
            
            var files = event.target.files; //FileList object
            var output = document.getElementById("result");
            
            for(var i = 0; i< files.length; i++)
            {
                var file = files[i];
                
                //Only pics
                if(!file.type.match('image'))
                  continue;
                
                var picReader = new FileReader();
                
                picReader.addEventListener("load",function(event){
                    
                    var picFile = event.target;
                    
                    var div = document.createElement("div");
                    
                    div.innerHTML = "<img class='thumbnail' src='" + picFile.result + "'" +
                            "title='" + picFile.name + "'/>";
                    
                    output.insertBefore(div,null);            
                
                });
                
                 //Read the image
                picReader.readAsDataURL(file);
            }                               
           
        });
    }
    else
    {
        console.log("Your browser does not support File API");
    }
}