bad.js

  /**
   * Iterate collection using callback _fn_,
   * passing both the value and index.
   *
   * @param  {function} fn
   * @return {Collection}
   * @api public
   */
  
  each: function(fn) {
    try {
      if (this.arr.forEach) {
        this.arr.forEach(fn)
      } else {
        for (var key in this.arr) {
          if (this.arr.hasOwnProperty(key)) {
            fn(this.arr[key], key)
          }
        }
    }
    catch (e) {
      if (e != $break) throw e
    }
    return this
  }

good.js

  /**
   * Iterate collection using callback _fn_,
   * passing both the value and index.
   *
   * @param  {function} fn
   * @return {Collection}
   * @api public
   */
  
  each: function(fn) {
    try {
      if (this.arr.forEach)
        this.arr.forEach(fn)
      else
        for (var key in this.arr)
          if (this.arr.hasOwnProperty(key))
            fn(this.arr[key], key)
    }
    catch (e) {
      if (e != $break) throw e
    }
    return this
  }