//document.write("Hello,JavaScript!我是韋幻");中語句功能是輸出文本，就是讓瀏覽器輸出“"Hello,JavaScript!我是韋幻"”。
JavaScript腳本可以放在網頁的head裏或者body部分，顯示效果也不一樣
“//”是JavaScript的註釋符號,單行註釋。
/*.....*/是JavaScript的多行註釋。
<html>
<body><script type = "text/JavaScript">
document.write("Hello,JavaScript!我是韋幻");
//document.write("Hello,JavaScript!我是韋幻");
<!--
//document.write("Hello,JavaScript!我是韋幻");
-->
</script>
</body>
</html>
<h1>、<h2>、<h3>、<h4>、<p>,符合html的語法規則
<html>
<body>
<script type = "text/JavaScript">
document.write("<h1>This is a header1</h1>");
document.write("<h2>This is a header2</h2>");
document.write("<h3>This is a header3</h3>");
document.write("<h4>This is a header4</h4>");
document.write("<p>This is a paragraph</p>");
document.write("<p>This is another paragraph</p>");
</script>
</body>
</html>
