How to count selected files

pure javascript:

document.getElementById("my_id").addEventListener("change", function() {
    console.log(this.files.length);
});

in case of input type file the value is stored in array as files with key name.

$('input#my_id').change(function(){
    var files = $(this)[0].files;
    if(files.length > 10){
        alert("you can select max 10 files.");
    }else{
        alert("correct, you have selected less than 10 files");
    }
});

fiddle example : http://jsfiddle.net/nze2B/3/