Actually, almost all browsers have a feature to control the characters on the web pages you visit, by pressing the Ctrl keytogether with + (to zoom in) or - (to zoom out). But there is one otherway of adding such a function "dynamic font size" on your site usingjavascript. Here is a script that can be used to facilitate the visitors tocontrol the font size of text on each page of your website/blog. Thiswill be very useful for readers who struggle with small letters, andallow the person to enlarge the font size of your writing, so they areeasier to read.
<script type="text/javascript">var min=8;var max=18;function zoominLetter() { var p = document.getElementsByTagName('p'); for(i=0;i<p.length;i++) { if(p[i].style.fontSize) { var s = parseInt(p[i].style.fontSize.replace("px","")); } else { var s = 12; } if(s!=max) { s += 1; } p[i].style.fontSize = s+"px" }}function zoomoutLetter() { var p = document.getElementsByTagName('p'); for(i=0;i<p.length;i++) { if(p[i].style.fontSize) { var s = parseInt(p[i].style.fontSize.replace("px","")); } else { var s = 12; } if(s!=min) { s -= 1; } p[i].style.fontSize = s+"px" }}</script>
The script above will change the font size of text within theparagraph (tag <p>). If you want to use another tag, you canchange the getElementsByTagName('p'); Of course, this script only works on the page with pixel sized fonts (letter-sized pixels (px)) compared with relative sized fonts(the relative size of the letters like: "em" and "%"). In addition, ifthe script does not find the font size of a paragraph, it will use thestandard size, which is 12px. How To Use :Enter the above script on your blog page (either by typing in the tag <head>or by using .js file external and import). To call the functionzoominLetter and zoomoutLetter you can use the following HTML code: <a href="javascript:zoominLetter();">A</a><a href="javascript:zoomoutLetter();">a</a>
tips: You can change the text A | a with other signs, or replace it with a picture by using tags <img>. Source: http://www.situsinformasiinternet.com/2010/01/controlling-font-size-blogwebsite-with-javascript.html | 
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