script_cwd_bench.htm

<script>
function run(fn, arg){
  var start = new Date;
  for(var i = 1e4; i--;) fn(arg);
  return new Date - start;
}
var tests = [function(src){
  return src.slice(0, src.lastIndexOf("/") + 1);
}, function(src){
  var a = src.split("/");
  a.pop();
  return a.join("/") + "/";
}, function(src){
  return src.split("/").slice(0, -1).join("/") + "/";
}, function(src){
  return /^.+\//.exec(src)[0];
}, function(src){
  return src.replace(/[^/]+$/, "");
}];
var src = "http://example.com/lab/test.js";
for(var t, i = -1; t = tests[++i];){
  if(t(src) !== "http://example.com/lab/") throw t;
  tests[i] += " -> " + run(t, src);
}
document.write("<pre>" + tests.join("\n\n"));
</script>