書中附帶的測試代碼如下
複製代碼 代碼如下:<html>
<head>
<title>Example</title>
</head>
<body>
<p><strong>Note:</strong> The latest versions of Firefox seem to have fixed the string concatenation problem. If you are using Firefox 1.0 or later, the string buffer may actually take longer than normal string concatenation.</p>
<script type="text/javascript">
function StringBuffer() {
this.__strings__ = new Array;
}
StringBuffer.prototype.append = function (str) {
this.__strings__.push(str);
};
StringBuffer.prototype.toString = function () {
return this.__strings__.join("");
};
var d1 = new Date();
var str = "";
for (var i=0; i < 10000; i++) {
str += "text";
}
var d2 = new Date();
document.write("Concatenation with plus: " + (d2.getTime() - d1.getTime()) + " milliseconds");
var buffer = new StringBuffer();
d1 = new Date();
for (var i=0; i < 10000; i++) {
buffer.append("text");
}
var result = buffer.toString();
d2 = new Date();
document.write("<br />Concatenation with StringBuffer: " + (d2.getTime() - d1.getTime()) + " milliseconds");
</script>
</body>
</html>
在 Firefox/3.0.3中執行的結果如下：
Concatenation with plus: 5 milliseconds
Concatenation with StringBuffer: 10 milliseconds
在IE6中執行結果如下：
Concatenation with plus: 234 milliseconds
Concatenation with StringBuffer: 62 milliseconds
1.兩種方式效能差別很大
2.看來IE6字串串連處理能力比FF3很差呀
3.IE6和FF3兩種方式結果相反，看來以後寫串連最佳化還有注意瀏覽器呀
