User:Edokter/FontSizer.js

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Documentation for this user script can be added at User:Edokter/FontSizer. This user script seems to have an accompanying .css page at User:Edokter/FontSizer.css.

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var fontsizerbuttons =
  '<li id="fontsizer">' +
    '<input type="submit" id="fontsizer-minus" name="minus" value="−" onclick="clickMinus()">' +
    '<input type="submit" id="fontsizer-reset" name="reset" value="100%" onclick="clickReset()">' +
    '<input type="submit" id="fontsizer-plus" name="plus" value="+" onclick="clickPlus()">' +
  '</li>';

var bodytag = document.getElementsByTagName('body')[0];

function updateButton(size) {
  var buttonval = document.getElementById('fontsizer-reset');
  buttonval.value = size + '%';
}

function clickMinus() {
  var currentSize = bodytag.style.fontSize.replace('%', '');
  if (!currentSize) {
    currentSize = 100;
  }
  if (currentSize > 100) {
    currentSize -= 10;
  } else {
    currentSize -= 5;
  }
  bodytag.style.fontSize = currentSize + '%';
  updateButton(currentSize);
}

function clickReset() {
  bodytag.style.fontSize = '100%';
  updateButton(100);
}

function clickPlus() {
  var currentSize = bodytag.style.fontSize.replace('%', '');
  if (!currentSize) {
    currentSize = 100;
  }
  if (currentSize < 100) {
    currentSize += 5;
  } else {
    currentSize += 10;
  }
  bodytag.style.fontSize = currentSize + '%';
  updateButton(currentSize);
}

$(function() {
  $('div#p-personal ul').append(fontsizerbuttons);
});