JavaScript files.length在ie9中不起作用需要替代方法

Question

I have the following JavaScript function which is failing in internet explorer 9 on the line which declares the variable filesattached .

function VesselDetails() {      

    insurancestart = $('#ctl00_ContentPlaceHolder1_datetimepickerinsstart').val();
    insuranceend = $('#ctl00_ContentPlaceHolder1_datetimepickerinsend').val();
    filesattached = $("input:File")[0].files.length;  

    //set up JS objects
    $('#ctl00_ContentPlaceHolder1_datetimepickerinsend').datetimepicker({ format: 'd/m/Y H:i a' });
    $('#ctl00_ContentPlaceHolder1_datetimepickerinsstart').datetimepicker({ format: 'd/m/Y H:i a' });

    //subscribe to change events
    $('#ctl00_ContentPlaceHolder1_datetimepickerinsstart').change(function () {
        insurancestart = $("ctl00_ContentPlaceHolder1_datetimepickerinsstart").val();
    });

    $('#ctl00_ContentPlaceHolder1_datetimepickerinsend').change(function () {
        insuranceend = $("ctl00_ContentPlaceHolder1_datetimepickerinsend").val();
    });

    $("input:File").change(function () {
        filesattached = $("input:File")[0].files.length;
    });

    ins_client();
}

The ins_client method looks like this:

function ins_client(sender, e) {
    if (pagemode == 'EditVessel') {
        e.IsValid = true;
    }

    if (pagemode == 'NewVessel') {
        if (insurancestart !== '' && insuranceend !== '' && filesattached > 0) {
            e.IsValid = true;
        }
        else {
            e.IsValid = false;
        }
    }
}

This all works perfectly well in chrome and ie 11 but the length property is returning an undefined for ie 9. I am using the length because I only want the page to be valid for a new vessel request once a document has been submitted, is there another way of doing this which will work in ie 9 onwards and chrome, apologies if this has already been answered elsewhere but I cannot find a workaround anywhere that enables this to continue working in the same way but in ie9 onwards and chrome.

Answer 1

I replaced:

filesattached = $("input:File")[0].files.length;  

With:

var areFilesAttached = document.getElementById('ctl00_ContentPlaceHolder1_fuAttachment').value ? true : false;

Within the VesselDetails function.

Then replaced the if statement within ins_client with the following:

if (pagemode == 'NewVessel') {
        if (insurancestart !== '' && insuranceend !== '' && areFilesAttached == true) {
            e.IsValid = true;
        }
        else {
            e.IsValid = false;
        }
    }

This was an alternative approach which enabled me to check whether or not a file had been provided without using the files.length property which is not compatible with IE9 .

Answer 2

I'm afraid this can't be achieved, IE9 does not support HTML5 File API and therefore it returns undefined value for files property.

Take a look at FILE API