<button id="btn_Test" onclick="alert("This a test button !")">测试</button>

什么意思呢？？

一看就错了
onclick="alert("This a test button !")"
改成
onclick="alert('This a test button !')"

<input type="button" id="btn_Button" onclick="alert(this)" value="Test" />
<br/>


<br/>

<input type="button" id="btn_Button" onclick="alert(this.id)" value="Test" />
<input type="button" id="btn_Button" onclick="alert(this.value)" value="Test" />
<input type="button" id="btn_Button" onclick="alert(this.type)" value="Test" />
<input type="button" id="btn_Button" onclick="alert(this.outerHTML)" value="Test" />
<input type="button" id="btn_Button" onclick="alert(this.onclick)" value="Test" />

<script>function TestScript(){
        alert("sss");
}</script>

<script>onload=function (){alert("sss");}</script>