我有一个调用PHP文件的AJAX脚本。

PHP文件回声报是或不是，我想用字符串做逻辑比较。

在JavaScript中，我想在字符串比较中的responseText，看它是否是==是（或否）。但比较失败。

所以，我做的警报responseText的，而且它确实显示出是（或否）作为字符串。但我读这里的responseText的可能含有隐藏的空白字符，所以我做的responseText的字符串的长度，这表明该字符串的长度是比它要长4个字符。所以，我躲过了responseText的警报（越狱（responseText的）），它表明我有％0A和0D％（换行和换行）隐藏在responseText的字符串的结尾。

我读到这些字符添加由PHP的，但我也读到了额外的字符是不同的PHP版本/服务器之间的不同。

如何prevent不使用正则表达式这些额外的空格，因为正则表达式可能会删除故意空格？

请不要建议使用jQuery或MooTools的作为答案。

TIA

我读到这些字符添加由PHP的，但我也读到了额外的字符是不同的PHP版本/服务器之间的不同。

这是错误的。这是简单的验证：创建一个test.php的文件，写这篇文章，只有这样：＆LT; PHP的回声测试; （不含＆GT？ ; ）到它并执行它。不会有空格。

这些空格最有可能来自你的脚本。一个常见的​​错误是一个PHP结束标记之后留下一些尾随换行符（＆GT; ），这将导致一个新的生产线正在打印

确认包括所有文件之前或之后你做回声是; 不回应任何事情，没有一个＆GT;

要避免这一问题的最简单的方法是不使用PHP的关闭标签，在文件的结尾（他们是不是强制性的）。

I have an ajax script that calls a php file.

The php file echos "yes" or "no", I want to use the strings to do logical comparisons.

In the javascript, I want to compare the string in the responseText to see if it is == to "yes" (or "no"). But the comparison fails.

So I do the alert responseText, and it does show "yes" (or "no") as the string. But I read on here that the responseText might contain hidden whitespace characters, so I did the string length of responseText and it shows that the string length is 4 characters longer than what it should be. So I escaped the responseText alert(escape(responseText)) and it shows that I have %0A and %0D (newlines and line feeds) hidden at the end of the responseText string.

I read that these characters are added on by php, but I also read that the extra characters are different among different php versions/servers.

How to prevent these extra whitespaces without using regex, since regex might remove intentional whitespaces?

Please don't suggest using jquery or mootools as answers.

TIA

I read that these characters are added on by php, but I also read that the extra characters are different among different php versions/servers.

That's wrong. That's simple to verify: create a test.php file, write this and only this: <?php echo "test"; (without ?>) into it and execute it. There will be no whitespace.

These whitespaces most probably come from your scripts. A common error is to leave some trailing newlines after a closing php tags (?>), which results in a new line being printed.

Verify that all files included before or after you do echo "yes"; don't echo anything and don't have a trailing newline after a ?>.

The easiest way to avoid this problem is do not use php close tags at end of files (they are not mandatory).