SOURCE

function change(){
  document.getElementById('myAnchor').innerHTML="访问W3School";
  document.getElementById('myAnchor').href="http://www.w3school.com.cn";
  document.getElementById('myAnchor').target="_blank";
}
function getfocus(){
  document.getElementById('myAnchor').focus();
}
function losefocus(){
  document.getElementById('myAnchor').blur();
}

document.write(document.title+ "<br>");
document.write(document.URL + "<br>");
document.write(document.domain+ "<br>");
function getValue(){
  alert(document.getElementById('p-name').innerHTML);
}

<a href="www.baidu.com" id="myAnchor">访问百度</a>
<input type="button" onclick="change()" value="change" />

<input type="button" onclick="getfocus()" value="getfocus">
<input type="button" onclick="losefocus()" value="losefocus" />
<p id="p-name" onclick="getValue()">ddd</p>

a:active {color:green}