How to check an input type=“file” has a file or not using jquery?

问题

I have a file upload control <input id="File1" type="file" /> in my page... How to check an input type="file" has a file or not using jquery on click of a button upload?

回答1:

if (jQuery('#File1').val()) { /* There are files */ }

回答2:

You should use "required" instead of JQuery. By just one attribute it'll check input=file has file or not. Example:

<input type="file" required/>

回答3:

$('#upload').bind('click', function(e){
   if( $('#File1').val() != ""){
       // file selected
   }
   else{
       // no file selected
   }
});

来源：https://stackoverflow.com/questions/2642970/how-to-check-an-input-type-file-has-a-file-or-not-using-jquery