把相对路径换成绝对路径

str = '/a/b/../c/d/e/../f';
function func(str) {
    arr = str.split('/');
    var s;
    if(arr.indexOf('..') == -1){
        return str;
        
    }else{
        index = arr.indexOf('..');
        arr.splice(index-1,2);
        s = arr.join('/'); 
        return arguments.callee(s);
    } 
    
}

console.log(func(str));