Change font size on my website with Javascript

Question

This is my website http://natjecanje.interes.hr/

I want to have big A and small A and by pressing one of this "A" people can change all letters size on website, all elements need change font size, Thank you! :)

P.S. I did google search, but i didn't find what i was looking for.

What did you try? there is a big problem about that though: do you need to mantain proportions? — briosheje, Apr 09 '15 at 15:11
Take a look at this: [Change Text Size On Click With JavaScript](http://davidwalsh.name/change-text-size-onclick-with-javascript) although I would advise against this idea. You should never let the user control the display/layout of your website. Make the font something readable by default, and if the user wants the font to be bigger they can zoom in with their browser. — APAD1, Apr 09 '15 at 15:12
I try with this http://davidwalsh.name/change-text-size-onclick-with-javascript But that code change only few thing on my website... i mean only few texts change their size with that script... i want all elements change size by klicking A+ and A- — Jan Novak, Apr 09 '15 at 15:13
@APAD1 Yeah I agree, but this is for my school project and that needs to be included :/ — Jan Novak, Apr 09 '15 at 15:14

score 0 · Answer 1 · answered Apr 09 '15 at 15:21

You need to use 2 differents CCS Style, a little JS script

Please Find below Javascript :

function setActiveStyleSheet(title) {
var i, a, main;
for(i=0; (a = document.getElementsByTagName("link")); i++) {
if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title")) {
a.disabled = true;
if(a.getAttribute("title") == title) a.disabled = false;
}
}
if (navigator.appName == "Microsoft Internet Explorer") {
window.resizeBy(0,-10);
window.resizeBy(0,+10);
}
}
function getActiveStyleSheet() {
  var i, a;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title") && !a.disabled) return a.getAttribute("title");
  }
  return null;
}

function getPreferredStyleSheet() {
  var i, a;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1
       && a.getAttribute("rel").indexOf("alt") == -1
       && a.getAttribute("title")
       ) return a.getAttribute("title");
  }
  return null;
}

function createCookie(name,value,days) {
  if (days) {
    var date = new Date();
    date.setTime(date.getTime()+(days*24*60*60*1000));
    var expires = "; expires="+date.toGMTString();
  }
  else expires = "";
  document.cookie = name+"="+value+expires+"; path=/";
}

function readCookie(name) {
  var nameEQ = name + "=";
  var ca = document.cookie.split(';');
  for(var i=0;i < ca.length;i++) {
    var c = ca[i];
    while (c.charAt(0)==' ') c = c.substring(1,c.length);
    if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
  }
  return null;
}

window.onload = function(e) {
  var cookie = readCookie("style");
  var title = cookie ? cookie : getPreferredStyleSheet();
  setActiveStyleSheet(title);
}

window.onunload = function(e) {
  var title = getActiveStyleSheet();
  createCookie("style", title, 365);
}

var cookie = readCookie("style");
var title = cookie ? cookie : getPreferredStyleSheet();
setActiveStyleSheet(title);

You can save this script in a fil named : changement_css.js

Now you need a first CCS style whit regular font-size, and another one with a different font size, and include it in your HTML file.

<!--Default CSS-->

<link rel="stylesheet" type="text/css" href="normal.css" title="normal">

<!--Alternate CSS-->

<link rel="alternate stylesheet" type="text/css" href="grand.css" title="grand">

Copy those line instead of your regular CSS Then, use this code to call your JS after your CSS link :

<script language="JavaScript" src="changement_css.js" type="text/javascript"></script>

Then, you need a button to change font-size :

<ul>

<li><a href="#" onclick="setActiveStyleSheet('normal'); return false;">Normal</a></li>

<li><a href="#" onclick="setActiveStyleSheet('grand'); return false;">Grand</a></li>

</ul>

I hope this could help you.

This message is translate from : http://forum.alsacreations.com/topic-6-11551-1-Boutons-AugmenterDiminuer-la-Taille-du-Texte-.html

cookies are not necessary, that si more code which I don't need in school project :/ and that JS I can't get till tomorrow :/ — Jan Novak, Apr 09 '15 at 15:34

score 0 · Answer 2 · answered Apr 10 '15 at 08:22

function promjenaVelicineFonta(inc) 
{ 
var p = document.getElementsByTagName('p'); 
for(n=0; n<p.length; n++) { 
if(p[n].style.fontSize) { 
var size = parseInt(p[n].style.fontSize.replace("px", "")); 
} else { 
var size = 14; 
} 
p[n].style.fontSize = size+inc + 'px'; 
} 

var span = document.getElementsByTagName('span'); 
for(n=0; n<span.length; n++) { 
if(span[n].style.fontSize) { 
var size = parseInt(span[n].style.fontSize.replace("px", "")); 
} else { 
var size = 14; 
} 
span[n].style.fontSize = size+inc + 'px'; 
} 
}

I found a solution, here it is.

score -1 · Answer 3 · edited May 23 '17 at 12:28

-1

Do you mean font size (i.e. 10pt, 12pt etc) or font capitalisation (i.e. a or A)? I think you mean capitalisation based on the theme of your question (because you said 'big' and 'small')?

You can control capitalisation with CSS via the 'text-transform' property (http://www.w3schools.com/cssref/pr_text_text-transform.asp).

You can use JavaScript to add remove CSS classes which is outlined in this thread: Change an element's class with JavaScript

Using this approach you could add remove CSS classes which use text-transform to change the capitalisation of the font.

edited May 23 '17 at 12:28

Community

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1

answered Apr 09 '15 at 15:14

Martin Kearn

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I mean on font-size for ex. normal is 16 and by pressing A+ it will become 17px on whole page – Jan Novak Apr 09 '15 at 15:16
OK, but the approach is still valid - just replace text-transform for font-size – Martin Kearn Apr 10 '15 at 13:43

Change font size on my website with Javascript

3 Answers3