<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>无标题文档</title> <script> window.onload=function(){ var oBtn1=document.getElementById('btn1'); var oBtn2=document.getElementById('btn2'); var oBtn3=document.getElementById('btn3'); var oDiv=document.getElementById('div1'); var aCh=oDiv.getElementsByTagName('input'); oBtn1.onclick=function(){ for(var i=0;i<aCh.length;i++){ aCh[i].checked=true; } }; oBtn2.onclick=function(){ for(var i=0;i<aCh.length;i++){ aCh[i].checked=false; } }; oBtn3.onclick=function(){ for(var i=0;i<aCh.length;i++){ if(aCh[i].checked==true){//这里用==双等号 aCh[i].checked=false; } else{ aCh[i].checked=true; } } }; }; </script> </head> <body> <input id="btn1" type="button" value="全选" /> <input id="btn2" type="button" value="不选" /> <input id="btn3" type="button" value="反选" /> <div id="div1"> <input type="checkbox" /><br/> <input type="checkbox" /><br/> <input type="checkbox" /><br/> <input type="checkbox" /><br/> <input type="checkbox" /><br/> <input type="checkbox" /><br/> </div> </body> </html>