<!DOCTYPE html>
<html>
<body>
<h1>JavaScript 运算符</h1>
<p>+ 运算符级联（相加）字符串。</p>
<p id="demo"></p>
<script>
var txt1 = "What a very";
var txt2 = "nice day";
document.getElementById("demo").innerHTML = txt1 + " " + txt2;
</script>
</body>
</html>