修剪字符串中的特定字符

一行就足够了：

var x = '|f|oo||';
var y = x.replace(/^\|+|\|+$/g, '');
document.write(x + '<br />' + y);

^     beginning of the string
\|+   pipe, one or more times
|     or
\|+   pipe, one or more times
$     end of the string

一般解决方案：

function trim (s, c) {
  if (c === "]") c = "\\]";
  if (c === "^") c = "\\^";
  if (c === "\\") c = "\\\\";
  return s.replace(new RegExp(
    "^[" + c + "]+|[" + c + "]+$", "g"
  ), "");
}

chars = ".|]\\^";
for (c of chars) {
  s = c + "foo" + c + c + "oo" + c + c + c;
  console.log(s, "->", trim(s, c));
}

参数应为字符（长度为 1 的字符串）。c

正如注释中提到的，支持多个字符可能很有用，因为例如修剪多个类似空格的字符是很常见的。为此，MightyPork 建议将 s 替换为以下代码行：if

c = c.replace(/[-/\\^$*+?.()|[\]{}]/g, '\\$&');

此部分是正则表达式语法中的一组特殊字符，是代表匹配字符的占位符，这意味着该函数转义特殊字符。在浏览器控制台中试用：[-/\\^$*+?.()|[\]{}]$&replace

> "{[hello]}".replace(/[-/\\^$*+?.()|[\]{}]/g, '\\$&')
"\{\[hello\]\}"

更新：我对不同解决方案的性能感到好奇，所以我在这里更新了一个基本的基准：https://www.measurethat.net/Benchmarks/Show/12738/0/trimming-leadingtrailing-characters

在Chrome下运行的一些有趣且意想不到的结果。https://www.measurethat.net/Benchmarks/ShowResult/182877

+-----------------------------------+-----------------------+
| Test name                         | Executions per second |
+-----------------------------------+-----------------------+
| Index Version (Jason Larke)       | 949979.7 Ops/sec      |
| Substring Version (Pho3niX83)     | 197548.9 Ops/sec      |
| Regex Version (leaf)              | 107357.2 Ops/sec      |
| Boolean Filter Version (mbaer3000)| 94162.3 Ops/sec       |
| Spread Version (Robin F.)         | 4242.8 Ops/sec        |
+-----------------------------------+-----------------------+

请注意;测试仅对单个测试字符串执行（前导和尾随字符都需要修剪）。此外，此基准测试仅提供原始速度的指示;其他因素（如内存使用情况）也很重要。

如果您正在处理较长的字符串，我相信通过将分配的字符串数量减少到零或一，这应该优于大多数其他选项：

function trim(str, ch) {
    var start = 0, 
        end = str.length;

    while(start < end && str[start] === ch)
        ++start;

    while(end > start && str[end - 1] === ch)
        --end;

    return (start > 0 || end < str.length) ? str.substring(start, end) : str;
}

// Usage:
trim('|hello|world|', '|'); // => 'hello|world'

或者，如果要从一组多个字符中修剪：

function trimAny(str, chars) {
    var start = 0, 
        end = str.length;

    while(start < end && chars.indexOf(str[start]) >= 0)
        ++start;

    while(end > start && chars.indexOf(str[end - 1]) >= 0)
        --end;

    return (start > 0 || end < str.length) ? str.substring(start, end) : str;
}

// Usage:
trimAny('|hello|world   ', [ '|', ' ' ]); // => 'hello|world'
// because '.indexOf' is used, you could also pass a string for the 2nd parameter:
trimAny('|hello| world  ', '| '); // => 'hello|world'

编辑：为了好玩，修剪单词（而不是单个字符）

// Helper function to detect if a string contains another string
//     at a specific position. 
// Equivalent to using `str.indexOf(substr, pos) === pos` but *should* be more efficient on longer strings as it can exit early (needs benchmarks to back this up).
function hasSubstringAt(str, substr, pos) {
    var idx = 0, len = substr.length;

    for (var max = str.length; idx < len; ++idx) {
        if ((pos + idx) >= max || str[pos + idx] != substr[idx])
            break;
    }

    return idx === len;
}

function trimWord(str, word) {
    var start = 0,
        end = str.length,
        len = word.length;

    while (start < end && hasSubstringAt(str, word, start))
        start += word.length;

    while (end > start && hasSubstringAt(str, word, end - len))
        end -= word.length

    return (start > 0 || end < str.length) ? str.substring(start, end) : str;
}

// Usage:
trimWord('blahrealmessageblah', 'blah');