console
function byname(){
alert(document.getElementsByName('text').length);
}
function createNewDoc(){
var newDoc=document.open("text/html","replace");
var txt="<html><body>学习dom很有趣</body></html>";
newDoc.write(txt);
newDoc.close();
}
document.write(document.anchors.length+"<br>");
document.write(document.forms.length);
function checked(){
document.getElementById("checkbox1").checked=true
}
function unchecked(){
document.getElementById('checkbox1').checked=false;
}
<div class="div1">
<input type="text" name="text" />
<input type="text" name="text" />
<input type="text" name="text" />
<input type="text" name="text" />
<input type="button" onclick="byname()" value="click"/>
</div>
<div class="div2">
<input type="button" value="打开并写入一个新文档" onclick="createNewDoc()"/>
</div>
<div class="div3">
<a href="#" class="" name="">1111</a>
<a href="#" class="" name="">1222</a>
<a href="#" class="" name="">1333</a>
<a href="#" class="" name="">1444</a>
</div>
<div class="div4">
<form action="">dd</form>
<form action="">dd</form>
<form action="">dd</form>
<form action="">dd</form>
</div>
<div class="div5">
<input type="checkbox" id="checkbox1"/>
<input type="button" onclick="checked()"value="checked"/>
<input type="button" onclick="unchecked()"value="unchecked"/>
</div>
.div1{
display:none;
}