很多政府网站内容页面经常需要增加减少字号，具体实现方法如下：

首先，设置两个按钮，点击按钮可增加或减小字号！

<span style="margin-left:30px;">字体：<a onclick="add()" style="font-size:18px;font-weight:bold;" href="javascript:SetFont()">A+</a> 

<a onclick="min()" style="font-size:16px;font-weight:bold;" href="javascript:SetFont()">A-</a> 

  </span>

然后就是写js代码，

var isClick=false; var size=16; var maxsize=22; var minsize=14; function add(){ isClick = true; if(size>=maxsize){alert("不能再大了！！！")} else{ size+=1; } } function min(){ isClick = true; if(size<=minsize){alert("不能再小了！！！")} else{size-=1;} } function SetFont() { var FontArea = document.getElementById("nr");//给内容范围设置一个id nr if (isClick==true){ console.log("当前字体大小"+size+"px"); } else{ size=size; } if(!FontArea) { return; } FontArea.style = 'font-size:'+size+ 'px'; var tagname=["td","span","div","a","li","ul","ol","p","font","b","tr","strong","table","section","pre","article","h1","h2","h3","h4","h5","h6"]; var length=tagname.length;

//遍历数组中的元素，逐一赋予字号 for(var k=0;k<length;k++){ tag=FontArea.getElementsByTagName(tagname[k]); for(var i=0;i<tag.length;i++){ tag[i].style.fontSize=size+'px'; } } }