Calling from a javascript function another javascript function having return false;?

Question

I have this simple javascript function which calls other 2 functions:

<script type="text/javascript" language="javascript">

    function mainfunction() {
        function1()
        function2()
    }

    function function1() {
        if (//some test) {
            alert('test function1');
            return false;
        }
    }

   function function2() {
        if (//some test) {
            alert('test function2');
            return false;
        }
    }

</script>

i call mainfunction() like this:

<form id="form1" runat="server" onSubmit="return mainfunction()">

or like this:

<asp:Button ID="btntest" runat="server" Text="test button" OnClientClick="return mainfunction()" />

btntest is a button that just calls some class which redirects to another page.

The problem

if i directly call any of the 2 functions function1() or function2() then the button will not get executed, which is what i want. but...:
When i call mainfunction() then alert in each function works but return false; doesn't seem to work because the button unfortunately gets executed.

why is that? how can i call the 2 functions and let their return false; work?

Amberlamps · Accepted Answer · 2013-03-03 21:52:05Z

1

Your mainfunction is not returning anything. Try this:

function mainfunction() {
    return function1() && function2();
}

As mentioned in the comments, to have your mainfunction working properly, you have to alter your other functions to always return either true or false:

function function1() {
    if (//some test) {
        alert('test function1');
        return false;
    }
    return true;
}

EDIT A funny hack to have both functions being executed and still return true only when both functions are true:

function mainfunction() {
    return (function1() + function2()) === 2;
}

edited Mar 3, 2013 at 21:52

answered Mar 3, 2013 at 21:18

Amberlamps

40.7k6 gold badges46 silver badges54 bronze badges

Sign up to request clarification or add additional context in comments.

12 Comments

icktoofay Over a year ago

function1 returns undefined or false, not true or false. undefined is not truthy, so function2 will never be called.

Amberlamps Over a year ago

@icktoofay: Okay, I should have said that you have to extend your functions by returning true. I will fix that. Thanks for the hint.

compliance Over a year ago

Thank you Amberlamps and icktoofay. I tried the solution: i changed mainfunction and the other 2 functions as mentioned but now unfortunately only function1 is called.

compliance Over a year ago

thank you guys, now function2 is called regardless if function1 fails or not. but this made me lost a bit, I don't really understand the purpose of the hack.

compliance Over a year ago

also i notice that it won't work unless i call mainfunction like this: return mainfunction()

|

AD7six · Accepted Answer · 2013-03-03 21:17:22Z

0

mainfunction doesn't return anything, you aren't using the return values from either function1 or function2

To prevent a form from submitting, you need the handler itself to return false, for example:

function mainfunction() {
    function1();
    function2();

    return false; // prevent form submission
}

Returning undefined (what you're doing right now in the example in the question) is not sufficient.

answered Mar 3, 2013 at 21:17

AD7six

67.2k14 gold badges121 silver badges167 bronze badges

1 Comment

compliance Over a year ago

Thank you AD7six, but the result is not always false. However thank you as I see what you mean, mainfunction didn't return anything.

Łukasz Adamus · Accepted Answer · 2013-03-03 21:31:02Z

0

Try this:

<asp:Button ID="btntest" runat="server" Text="test button" OnClientClick="mainfunction(); return false;" />

This will works as well:

<asp:Button ID="btntest" runat="server" Text="test button" OnClientClick="return mainfunction();" />

but you will need to change mainfunction:

function mainfunction() {
    function1();
    function2();
    return false;
}

answered Mar 3, 2013 at 21:31

Łukasz Adamus

2666 silver badges19 bronze badges

1 Comment

compliance Over a year ago

Thank you for your answer, it made me realize that i must also use return when calling mainfunction(). however mainfunction() does not always return false.

Collectives™ on Stack Overflow

Calling from a javascript function another javascript function having return false;?

The problem

3 Answers 3

12 Comments

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

The problem

3 Answers 3

12 Comments

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related