方法说明：

输出规范格式的path字符串。

语法：

复制代码 代码如下:
path.normalize(p)

由于该方法属于path模块，使用前需要引入path模块（var path= require(“path”) ）

例子：

复制代码 代码如下:
path.normalize('/foo/bar//baz/asdf/quux/..')
// returns
'/foo/bar/baz/asdf'

源码：

复制代码 代码如下:
// windows version
exports.normalize = function(path) {
var result = splitDeviceRe.exec(path),
device = result[1] || '',
isUnc = device && device.charAt(1) !== ':',
isAbsolute = exports.isAbsolute(path),
tail = result[3],
trailingSlash = /[\\\/]$/.test(tail);

// If device is a drive letter, we'll normalize to lower case.
if (device && device.charAt(1) === ':') {
device = device[0].toLowerCase() + device.substr(1);
}

// Normalize the tail path
tail = normalizeArray(tail.split(/[\\\/]+/).filter(function(p) {
return !!p;
}), !isAbsolute).join('\\');

if (!tail && !isAbsolute) {
tail = '.';
}
if (tail && trailingSlash) {
tail += '\\';
}

// Convert slashes to backslashes when `device` points to an UNC root.
// Also squash multiple slashes into a single one where appropriate.
if (isUnc) {
device = normalizeUNCRoot(device);
}

return device + (isAbsolute ? '\\' : '') + tail;
};