Hiding element with reflow in JavaScript and how is it different from CSS hidden property?

Question

I have two buttons, one passes true argument, another does not. Both buttons disappear when I press on them. But what exactly is going on behind the scenes for each button?

If this code looks familiar to you, it's from JavaScript: The Definitive Guide 6th Edition. Great book!

One more thing. In C++ and Java omitting an argument would result in a compile-error. In C# you could change the second argument to be optional and it would work. In JavaScript I didn't have to do that. Are all arguments in JavaScript optional?

JavaScript:

function hide(e, reflow) {
    if (reflow) {
        e.style.display = "none";
    }
    else {
        e.style.visibility = "hidden";
    }
}

HTML:

<button onclick="hide(this,true); debug('hide button 1');">Hide1</button>
<button onclick="hide(this); debug('hide button 2');">Hide2</button>

I don't get your question. Behind the scenes: when you click button 1 - it disapears because of e.style.display = "none"; and when you click Button 2 - it disapears because of e.style.visibility = "hidden"; — Scherbius.com
– Scherbius.com, Commented May 10, 2011 at 17:30
@Dmitriy I am new to JavaScript and CSS. My question was what is the difference between the two statements. lord_t made it clear as to what happens when you do display = "none" and visibility = "hidden". — Sahat Yalkabov
– Sahat Yalkabov, Commented May 10, 2011 at 17:35

pmaruszczyk · Accepted Answer · 2011-05-10 17:23:31Z

2

Yes, all arguments in JavaScript are optional.

With display:none is something similar to width:0; height:0, and if you set the visibility to hidden button stay on it's place, but it is invisible.

answered May 10, 2011 at 17:23

pmaruszczyk

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Sahat Yalkabov Over a year ago

I've made my 2nd button 500px wide to see the difference and it's clear to me now. Thanks!

Adilson de Almeida Jr · Accepted Answer · 2011-05-10 17:25:00Z

1

Yeap!

In Javascript you have all arguments optional. Actually you don´t need to name your arguments. There is a implicit var called "arguments" where you can find an array of your arguments. You can ever access your arguments through this var.

Take a look at: https://developer.mozilla.org/en/JavaScript/Reference/functions_and_function_scope/arguments

answered May 10, 2011 at 17:25

Adilson de Almeida Jr

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Adilson de Almeida Jr Over a year ago

And about the main question: - visibility: you can hide your element and preserve the space where it was, leaving a empty gap in the layout; - display: you can control how your control will appears on the page, as a block, as an inline element, or even so, hiding it;

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