Observe the performance difference between finally and catch

try-catch-finally-stuff.js

'use strict';

const ITER = 1e7;


function parseArgs(args, start) {
  var arr = [];
  for (var i = start; i < args.length; i++)
    arr.push(args[i]);
  return arr;
}


function failSafely(ctx, cb, fail) {
  var args = undefined;
  var args_len = arguments.length;
  var ret;
  if (args_len > 6)
    args = parseArgs(arguments, 3);
  try {
    if (args_len > 6 || ctx)
      ret = cb.apply(ctx, args);
    if (args_len === 3)
      ret = cb();
    else if (args_len === 4)
      ret = cb(arguments[3]);
    else if (args_len === 5)
      ret = cb(arguments[3], arguments[4]);
    else if (args_len === 6)
      ret = cb(arguments[2], arguments[4], arguments[5]);
    else
      throw new Error('UNREACHABLE');
  // Switch to "finally"
  } catch(e) {
    if (args_len > 6 || ctx)
      fail.apply(ctx, args);
    if (args_len === 3)
      fail();
    else if (args_len === 4)
      fail(arguments[3]);
    else if (args_len === 5)
      fail(arguments[3], arguments[4]);
    else if (args_len === 6)
      fail(arguments[2], arguments[4], arguments[5]);
    else
      throw new Error('UNREACHABLE');
  }
  return ret;
}


function runner(n) {
  var n = (n % (-1 >>> 0)) >>> 0;
  var b = 4;
  while (b < n && b > 0) {
    if ((n & b) === b)
      n -= b;
    b <<= 3;
  }
  return n;
}


function failWell() { }

console.log(failSafely(null, runner, failWell, Math.random() * 1e15));


var t = process.hrtime();
for (var i = 0; i < ITER; i++) {
  failSafely(null, runner, failWell, Math.random() * 1e15);
}
t = process.hrtime(t);
console.log(((t[0] * 1e9 + t[1]) / ITER).toFixed(1) + ' ns/op');