Question

I have this url in javascript “/people/things/” I want a function that will only return “things” how do I do this?

I’ve tried ugly stuff. Like iterating but I get stuck when I have to figure out how to delete the rest of the string and its very slow asymptotically.

I keep getting “ILLEGAL”. Super annoying.

$(function() { 

    var parse = function(str) {

        var a = "";   
        if (str.length && str.length > 1) {

           str = str.slice(0, str.length -1);   //remove first

            for (var i = str.length; i > 1; i--) {
                if (str[i] !== '\\' ) {
                      a += str[i];
                    }

            }


        }

        return a;

    };   

       c = "\things\stuff\";
       alert(parse(c));        //result should be "things"                

});​

Answer 1

First of all, you could simplify your code using match() instead:

var s = "/people/things/";
var match = s.match(/\/([^/]+)\/$/);
var things = match[1]; // "things"

With respect to the ILLEGAL error, that’s because you forgot to escape the \ in your string. So instead of \things\stuff\, use \\things\\stuff\\.

Now, to your parse function. The general idea is correct, but you have a couple of implementation errors:

1. break out of the loop as soon as you find \\ (the else part of your if); otherwise, you’ll just skip the \, adding all other characters;
2. You are traversing the array from back to start, and adding each character to a string; thus, in the end, you’ll get a reversed string. To fix it, instead of using a += str[i], use a = str[i] + a.
3. i should start with a.length - 1, not a.length.

Here’s the final version:

var parse = function(str) {
  var a = '';   
  if (str.length && str.length > 1) {
    str = str.slice(0, str.length -1);
    for (var i = str.length - 1; i > 1; i--) {
      if (str[i] !== '\\' ) {
        a = str[i] + a;
      } else {
        break;   
      }
    }
  }
  return a;
};

DEMO.