修剪空白

要从字符串的边缘修剪空白，请使用 String.prototype.trim：

"    some whitespaced string  ".trim();  // "some whitespaced string"

许多 JavaScript 引擎，但不是 Internet Explorer ，已经实现了非标准的 trimLeft 和 trimRight 方法。对于标准化的 trimStart 和 trimEnd 方法，目前处于该过程的第 1 阶段的提议 ，为了兼容性而别名为 trimLeft 和 trimRight。

// Stage 1 proposal
"    this is me    ".trimStart();  // "this is me    "
"    this is me    ".trimEnd();  // "    this is me"

// Non-standard methods, but currently implemented by most engines
"    this is me    ".trimLeft();  // "this is me    "
"    this is me    ".trimRight();  // "    this is me"