如何检查用户是否在Javascript中上传了文件

Question

I have created a form in which I have 2 text fields and one File field. I have added Javascript on 'text' fields. If user left 'text' fields and press submit button, All Fields are RequiredFont turns red, I want to turn it red as well when user doesn't upload any Image. I have tried various ways but its not working. Kindly tell me the way of doing it.

      <script type="text/javascript">

function myFunction()
{
    var category_name   =   document.forms["insert"]["sub_category_name"].value;
    //var image =           document.forms["insert"]["file"].item();

    var error           =   document.getElementById("error");


    if(category_name=="" )
    {
        error.style.color="Red";
        return false;
        }
        else
        {
            //message.innerHTML="Data Inserted!";
            }
    }


</script>

PHP code

    <?php

echo "
    <form name='insert' action='sub_categories.php' method='POST' onSubmit='return myFunction()' enctype='multipart/form-data'>
        <table class='gridtable' border=2 bordercolor='#CCCCCC' cellpadding='10'>
        <tr>
        <th>
            Sub-Category Name: </th><td>    <input type='text' name='sub_category_name' ></td></tr>";





            echo "
        <tr>
        <th>
            Image1:</th><td> <input type='file' name= 'file' ></td></tr> 

            ";

Thanks

Answer 1

Just get your file input by id and check if it's value is empty :

if(document.getElementById('file').value=='') {//something here }