How can I ignore two null or unassigned values in jQuery?

Question

I have this code to compare two values to verify they are identical:

$(document).on("blur", "[id$=boxSection5Total]", function (e) {
    var totalvalue = $(this).val();
    var paymenttotalvalue = $('[id$=boxPaymentAmount]').val();
    if (totalvalue != paymenttotalvalue) {
        console.log("The value in 'Total' does not equal the previous value in 'Payment Total.'");
        alert("The value in 'Total' does NOT equal the previous value in 'Payment Total.' payment total is " + paymenttotalvalue + " and total is " + totalvalue);
    }
    else {
        console.log("The value in 'Total' DOES equal the previous value in 'Payment Total'");
    }
});

However, if both text elements are left blank, it fails - they are considered to not be equal (the "if (totalvalue != paymenttotalvalue)" condition is true).

How can I refactor the code so that it ignores cases where both elements have been left blank?

Something like:

$(document).on("blur", "[id$=boxSection5Total]", function (e) {
    var totalvalue = $(this).val();
    var paymenttotalvalue = $('[id$=boxPaymentAmount]').val();
    if ((totalvalue == null) & (paymenttotalvalue == null)) {
        return;
    }
    . . .
});

?

Both "boxSection5Total" and "boxPaymentAmount" are text elements (textboxes).

The value will not be 'null' and `"" == null` is false. The simplest - and most idiomatic - change to the existing would be `if (!totalvalue && !paymenttotalvalue) { return; }`, but likely better to combine with the other conditional. — user2864740, Jul 07 '15 at 22:09
@up true, if it comes from html form its mostly considered as empty value — itwasntme, Jul 07 '15 at 22:11

CommonKnowledge · Answer 1 · 2015-07-07T22:26:23.553

2

If these are in fact blank text values then use....

if(totalvalue === "" && paymenttotalvalue === "")
{
    return;
}

or (i think)

if(totalvalue == 1 && paymenttotalvalue == 1)
{
    return;
}

edited Jul 07 '15 at 22:26

answered Jul 07 '15 at 22:11

CommonKnowledge

769
1
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1

and === instead of == (e.g., false == "" is actually true) – bjfletcher Jul 07 '15 at 22:12
The getElementById won't work, because the Sharepoint elements have a bunch of greek, russian, bulgarian, etc. prepended to them, like "id=zorbaIvan_bulgarischesSemillaDe0143209870945634-boxSection5Total" – B. Clay Shannon-B. Crow Raven Jul 07 '15 at 22:21
Return a boolean in an event handler? – B. Clay Shannon-B. Crow Raven Jul 07 '15 at 22:24
@ B. Clay Shannon You can return what you want. The code I added was only supposed to be used as sudo code for the example. – CommonKnowledge Jul 07 '15 at 22:26
@CommonKnowledge: Okay, no sweat. – B. Clay Shannon-B. Crow Raven Jul 08 '15 at 14:55

score 2 · Accepted Answer · edited May 23 '17 at 12:06

2

If you want to check specifically on null you should try something like this.

if (totalvalue !== null && paymenttotalvalue !== null && totalvalue != paymenttotalvalue)

If you want to check for untruthy (also see here: JavaScript: how to test if a variable is not NULL) you can use this:

if (totalvalue && paymenttotalvalue && totalvalue != paymenttotalvalue)

edited May 23 '17 at 12:06

Community

1
1

answered Jul 07 '15 at 22:13

mwoelk

1,182
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How can I ignore two null or unassigned values in jQuery?

2 Answers2