Question

It is possible to check if a input was not changed using change() event?

I’m working with <input type='file' /> and i want to warning the user that no changes was made on his own action.

Right now, i just made a normal change() event:

 // fire the thumbnail (img preview)
$("#file-input").on("change", function () {
    readURL(this); // create the thumbnail
});

what i’m missing ?

Prev Solutuib:

well, i found a workaround for this, the real problem is that i give a option to the user to hide the thumbnail, and if he wants, open again…

but the thumbnail will only open when the user select a image, that’s the problem, because the change event fire this option to open, so, if no change, no thumbnail open.

so, when i hide the thumbnail, i change the input file for a new one, making the change event always fire.

Answer 1

Use a variable to store the last value of the input, and compare to the current value on change event, if they are the same, no change was made :

var last_value = $("#file-input").val();

$("#file-input").on("change", function () {
    if (this.value === last_value) alert('no change');
    last_value=this.value;
});

EDIT: Or you can always just replace the input tag with another, like this SO answer suggest :

var $c  = $("#container");
var $f1 = $("#container .f1");

function FChange() {
    alert("f1 changed");

    $(this).remove();
    $("<input type='file' class='f1' />").change(FChange).appendTo($c);
}

$f1.change(FChange);