js简单实现调整网页字体大小的方法

//var tgs = new Array('div','td','tr');
var tgs = new Array('td','tr');
//Specify spectrum of different font sizes:
//var szs = new Array( 'xx-small','x-small','small','medium','large','x-large','xx-large' );
var szs = new Array( '10px','12px','14px','16px','18px','20px','22px' );
var startSz = 2;
function tsize( trgt,inc ) {
  if (!document.getElementById)
  {
    return
  }
  var d = document,cEl = null,sz = startSz,i,j,cTags;
  //sz += inc;
  sz = inc;
  if ( sz < 0 )
  {
    sz = 0;
  }
  if ( sz > 6 )
  {
    sz = 6;
  }
  startSz = sz;
  if ( !( cEl = d.getElementById( trgt ) ) ) cEl = d.getElementsByTagName( trgt )[ 0 ];
  cEl.style.fontSize = szs[ sz ];
  for ( i = 0 ; i < tgs.length ; i++ )
  {
    cTags = cEl.getElementsByTagName( tgs[ i ] );
    for ( j = 0 ; j < cTags.length ; j++ )
    {
      cTags[ j ].style.fontSize = szs[ sz ];
    }
  }
}

<td width="13">
<a href="javascript:tsize('body',0)">
<img src="../image/fsize1of.gif"
name="fsize1" width="18" height="14" border="0" id="fsize1"
onMouseOver="MM_swapImage('fsize1','','../image/fsize1on.gif',1)"
onMouseOut="MM_swapImgRestore()"></a>
</td>