Javascript if/else question

Question

I wanna open a div and close it with this function but it doesnt work where is the wrong part i couldnt fix it, can anyone help me ?

function Element(id)
{    
    if(document.getElementById(id).style.display = 'block')
    {
        document.getElementById(id).style.display = 'block';
    }
    else
    {
        document.getElementById(id).style.display = 'none';
    }
}

Please format your code correctly by clicking the Format Code button in the toolbar. — SLaks
– SLaks, Commented Dec 17, 2010 at 17:39

SLaks · Accepted Answer · 2010-12-17 17:39:05Z

3

Your if statement assigns the property instead of comparing it.
Change = to ===.

answered Dec 17, 2010 at 17:39

SLaks

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2 Comments

charliegriefer Over a year ago

Just to clarify @SLaks' answer, = is an assignment operator (e.g. foo = "bar"). == and === are comparison operators (e.g. if ( foo == "bar").

psmay Over a year ago

Specifically, the = in the if(...) should be changed, but the others shouldn't.

m0sa · Accepted Answer · 2010-12-17 19:27:12Z

3

I would suggest you rewrite it with the ternary operator, its much more readable and maintainable:

var element = document.getElementById(id);
element.style.display = element.style.display === 'block' ? 'none' : 'block';

edited Dec 17, 2010 at 19:27

answered Dec 17, 2010 at 17:42

m0sa

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2 Comments

xj9 Over a year ago

Move the ? and the : up a line or you could be a victim of semicolon insertion.

KooiInc Over a year ago

@indieinvader: I don't think semicolon insertion would have occured in his first version, not even if he did put a return before the statement.

Andrei Andrushkevich · Accepted Answer · 2010-12-17 17:42:12Z

1

function Element(id) { 
        if( document.getElementById(id).style.display == 'block') {
             document.getElementById(id).style.display = 'block';
       } else { document.getElementById(id).style.display = 'none'; }
}

answered Dec 17, 2010 at 17:42

Andrei Andrushkevich

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Comments

C. Ross · Accepted Answer · 2010-12-17 18:08:05Z

1

Thank you ! This one worked.! but I changed the code inside of if. Because it says if you find block which should be none.

function Element(id) { 
    if( document.getElementById(id).style.display == 'none') {
      document.getElementById(id).style.display = 'block';
    } else { 
      document.getElementById(id).style.display = 'none'; 
    } 
}

edited Dec 17, 2010 at 18:08

C. Ross

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answered Dec 17, 2010 at 17:54

Extelliqent

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Comments

El Ronnoco · Accepted Answer · 2010-12-17 18:23:04Z

0

You don't need an else or a ternary operator as your first condition has no effect. So this will suffice...

if(document.getElementById(id).style.display != 'block')
{
    document.getElementById(id).style.display = 'none';
};

answered Dec 17, 2010 at 18:23

El Ronnoco

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1 Comment

El Ronnoco Over a year ago

Ah, I see your own answer has the action reversed so this no longer applies.

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