编程题: 自己实现bash realpath (化简绝对路径)

MacBook-Pro-5:bin luyu$ realpath /opt/X11/./../X11/.././X11/var/./log/../.././bin/
/opt/X11/bin

var path = ‘/opt/X11/./../X11/.././X11/var/./log/../.././bin/‘;
>>undefined
var str = [];
>>undefined
var arr = path.split(‘/‘);
>>undefined
for (var i = 1; i < arr.length; i++) {
    if (arr[i] === ‘.‘) continue;
    if (arr[i] === ‘..‘) {
        str.pop();
    } else {
        str.push(arr[i]);
    }
}
>>4
‘/‘ + str.join(‘/‘);
>>"/opt/X11/bin/"