Simple optimization of a compiled Jade template

JadeTmpltBench.js

self =
  {
  header: "Header",
  header2: "Header2",
  header3: "Header3",
  header4: "Header4",
  header5: "Header5",
  header6: "Header6",
  list: ['1', '2', '3', '4', '5', '6', '7', '8', '9', '10']
  };

attrs = function (obj, escaped) {
  var buf = []
    , terse = obj.terse;

  delete obj.terse;
  var keys = Object.keys(obj)
    , len = keys.length;

  if (len) {
    buf.push('');
    for (var i = 0; i < len; ++i) {
      var key = keys[i]
        , val = obj[key];

      if ('boolean' == typeof val || null == val) {
        if (val) {
          terse
            ? buf.push(key)
            : buf.push(key + '="' + key + '"');
        }
      } else if (0 == key.indexOf('data') && 'string' != typeof val) {
        buf.push(key + "='" + JSON.stringify(val) + "'");
      } else if ('class' == key && Array.isArray(val)) {
        buf.push(key + '="' + exports.escape(val.join(' ')) + '"');
      } else if (escaped[key]) {
        buf.push(key + '="' + exports.escape(val) + '"');
      } else {
        buf.push(key + '="' + val + '"');
      }
    }
  }

  return buf.join(' ');
};

attrs2 = function (obj, escaped) {
  var terse = obj.terse;

  delete obj.terse;
  var keys = Object.keys(obj)
    , len = keys.length;

  var s = ' ';
  if (len) {
    for (var i = 0; i < len; ++i) {
      var key = keys[i]
        , val = obj[key];

      if ('boolean' == typeof val || null == val) {
        if (val) {
          terse
            ? (s+=key)
            : (s+=key + '="' + key + '" ');
        }
      } else if (0 == key.indexOf('data') && 'string' != typeof val) {
        s += key + "='" + JSON.stringify(val) + "' ";
      } else if ('class' == key && Array.isArray(val)) {
        s += key + '="' + exports.escape(val.join(' ')) + '" ';
      } else if (escaped[key]) {
        s += key + '="' + exports.escape(val) + '" ';
      } else {
        s += key + '="' + val + '" ';
      }
    }
  }

  return s;
};

jt1 = function ()
  {
  //var attrs = jade.attrs, escape = jade.escape, rethrow = jade.rethrow;
  var buf = [];
  //var self = locals || {};
  var interp;
  buf.push('<div><h1');
  buf.push(attrs({ "class": ('header') }, {}));
  buf.push('>');
  var __val__ = self.header
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h1><h2');
  buf.push(attrs({ "class": ('header2') }, {}));
  buf.push('>');
  var __val__ = self.header2
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h2><h3');
  buf.push(attrs({ "class": ('header3') }, {}));
  buf.push('>');
  var __val__ = self.header3
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h3><h4');
  buf.push(attrs({ "class": ('header4') }, {}));
  buf.push('>');
  var __val__ = self.header4
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h4><h5');
  buf.push(attrs({ "class": ('header5') }, {}));
  buf.push('>');
  var __val__ = self.header5
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h5><h6');
  buf.push(attrs({ "class": ('header6') }, {}));
  buf.push('>');
  var __val__ = self.header6
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h6><ul');
  buf.push(attrs({ "class": ('list') }, {}));
  buf.push('>');
  // iterate self.list
  (function()
    {
    if ('number' == typeof self.list.length) 
      {
      for (var $index = 0, $$l = self.list.length; $index < $$l; $index++)
        {
        var item = self.list[$index];
        buf.push('<li');
        buf.push(attrs({ "class": ('item') }, {}));
        buf.push('>');
        var __val__ = item
        buf.push(null == __val__ ? "" : __val__);
        buf.push('</li>');
        }
      }
    else 
      {
      for (var $index in self.list)
        {
        if (self.list.hasOwnProperty($index))
          {
          var item = self.list[$index];

          buf.push('<li');
          buf.push(attrs({ "class": ('item') }, {}));
          buf.push('>');
          var __val__ = item
          buf.push(null == __val__ ? "" : __val__);
          buf.push('</li>');
          }
        }
      }
  }).call(this);
  buf.push('</ul></div>');return new Buffer(buf.join(""));
  }

jt2 = function ()
  {
  //var attrs = jade.attrs, escape = jade.escape, rethrow = jade.rethrow;
  //var self = locals || {};
  s ='<div><h1' + attrs2({ "class": ('header') }, {}) + '>';
  var __val__ = self.header;
  s += (null == __val__ ? "" : __val__) + '</h1><h2' + attrs2({ "class": ('header2') }, {}) + '>';
  var __val__ = self.header2;
  s += (null == __val__ ? "" : __val__) + '</h2><h3' + attrs2({ "class": ('header3') }, {}) + '>';
  var __val__ = self.header3;
  s += (null == __val__ ? "" : __val__) + '</h3><h4' + attrs2({ "class": ('header4') }, {}) + '>';
  var __val__ = self.header4;
  s += (null == __val__ ? "" : __val__) + '</h4><h5' + attrs2({ "class": ('header5') }, {}) + '>';
  var __val__ = self.header5;
  s += (null == __val__ ? "" : __val__) + '</h5><h6' + attrs2({ "class": ('header6') }, {}) + '>';
  var __val__ = self.header6;
  s += (null == __val__ ? "" : __val__) + '</h6><ul' + attrs2({ "class": ('list') }, {}) + '>';
  // iterate self.list
  (function()
    {
    if ('number' == typeof self.list.length) 
      {
      for (var $index = 0, $$l = self.list.length; $index < $$l; $index++)
        {
        var item = self.list[$index];
        s += '<li' + attrs2({ "class": ('item') }, {}) + '>';
        var __val__ = item;
        s += (null == __val__ ? "" : __val__) + '</li>';
        }
      }
    else 
      {
      for (var $index in self.list)
        {
        if (self.list.hasOwnProperty($index))
          {
          var item = self.list[$index];
          s += '<li' + attrs2({ "class": ('item') }, {}) + '>';
          var __val__ = item;
          s += (null == __val__ ? "" : __val__) + '</li>';
          }
        }
      }
  }).call(this);
  s += '</ul></div>';
  return new Buffer(s);
  }

jt3 = function ()
  {
  //var attrs = jade.attrs, escape = jade.escape, rethrow = jade.rethrow;
  //var self = locals || {};
  s ='<div><h1' + attrs2({ "class": ('header') }, {}) + '>';
  var __val__ = self.header;
  s += (null == __val__ ? "" : __val__);
  s += '</h1><h2';
  s += attrs2({ "class": ('header2') }, {});
  s += '>';
  var __val__ = self.header2;
  s += (null == __val__ ? "" : __val__);
  s += '</h2><h3';
  s += attrs2({ "class": ('header3') }, {});
  s += '>';
  var __val__ = self.header3;
  s += (null == __val__ ? "" : __val__);
  s += '</h3><h4';
  s += attrs2({ "class": ('header4') }, {});
  s += '>';
  var __val__ = self.header4;
  s += (null == __val__ ? "" : __val__);
  s += '</h4><h5';
  s += attrs2({ "class": ('header5') }, {});
  s += '>';
  var __val__ = self.header5;
  s += (null == __val__ ? "" : __val__);
  s += '</h5><h6';
  s += attrs2({ "class": ('header6') }, {});
  s += '>';
  var __val__ = self.header6;
  s += (null == __val__ ? "" : __val__);
  s += '</h6><ul';
  s += attrs2({ "class": ('list') }, {});
  s += '>';
  // iterate self.list
  (function()
    {
    if ('number' == typeof self.list.length) 
      {
      for (var $index = 0, $$l = self.list.length; $index < $$l; $index++)
        {
        var item = self.list[$index];
        s += '<li';
        s += attrs2({ "class": ('item') }, {});
        s += '>';
        var __val__ = item;
        s += (null == __val__ ? "" : __val__);
        s += '</li>';
        }
      }
    else 
      {
      for (var $index in self.list)
        {
        if (self.list.hasOwnProperty($index))
          {
          var item = self.list[$index];
          s += '<li';
          s += attrs2({ "class": ('item') }, {});
          s += '>';
          var __val__ = item;
          s += (null == __val__ ? "" : __val__);
          s += '</li>';
          }
        }
      }
  }).call(this);
  s += '</ul></div>';
  return new Buffer(s);
  }

jt4 = function ()
  {
  //var attrs = jade.attrs, escape = jade.escape, rethrow = jade.rethrow;
  //var self = locals || {};
  s ='<div><h1' + attrs({ "class": ('header') }, {}) + '>';
  var __val__ = self.header;
  s += (null == __val__ ? "" : __val__) + '</h1><h2' + ({ "class": ('header2') }, {}) + '>';
  var __val__ = self.header2;
  s += (null == __val__ ? "" : __val__) + '</h2><h3' + attrs({ "class": ('header3') }, {}) + '>';
  var __val__ = self.header3;
  s += (null == __val__ ? "" : __val__) + '</h3><h4' + attrs({ "class": ('header4') }, {}) + '>';
  var __val__ = self.header4;
  s += (null == __val__ ? "" : __val__) + '</h4><h5' + attrs({ "class": ('header5') }, {}) + '>';
  var __val__ = self.header5;
  s += (null == __val__ ? "" : __val__) + '</h5><h6' + attrs({ "class": ('header6') }, {}) + '>';
  var __val__ = self.header6;
  s += (null == __val__ ? "" : __val__) + '</h6><ul' + attrs({ "class": ('list') }, {}) + '>';
  // iterate self.list
  (function()
    {
    if ('number' == typeof self.list.length) 
      {
      for (var $index = 0, $$l = self.list.length; $index < $$l; $index++)
        {
        var item = self.list[$index];
        s += '<li' + attrs({ "class": ('item') }, {}) + '>';
        var __val__ = item;
        s += (null == __val__ ? "" : __val__) + '</li>';
        }
      }
    else 
      {
      for (var $index in self.list)
        {
        if (self.list.hasOwnProperty($index))
          {
          var item = self.list[$index];
          s += '<li' + attrs({ "class": ('item') }, {}) + '>';
          var __val__ = item;
          s += (null == __val__ ? "" : __val__) + '</li>';
          }
        }
      }
  }).call(this);
  s += '</ul></div>';
  return new Buffer(s);
  }

jt5 = function ()
  {
  //var attrs = jade.attrs, escape = jade.escape, rethrow = jade.rethrow;
  var buf = [];
  //var self = locals || {};
  var interp;
  buf.push('<div><h1');
  buf.push(attrs2({ "class": ('header') }, {}));
  buf.push('>');
  var __val__ = self.header
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h1><h2');
  buf.push(attrs2({ "class": ('header2') }, {}));
  buf.push('>');
  var __val__ = self.header2
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h2><h3');
  buf.push(attrs2({ "class": ('header3') }, {}));
  buf.push('>');
  var __val__ = self.header3
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h3><h4');
  buf.push(attrs2({ "class": ('header4') }, {}));
  buf.push('>');
  var __val__ = self.header4
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h4><h5');
  buf.push(attrs2({ "class": ('header5') }, {}));
  buf.push('>');
  var __val__ = self.header5
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h5><h6');
  buf.push(attrs2({ "class": ('header6') }, {}));
  buf.push('>');
  var __val__ = self.header6
  buf.push(null == __val__ ? "" : __val__);
  buf.push('</h6><ul');
  buf.push(attrs2({ "class": ('list') }, {}));
  buf.push('>');
  // iterate self.list
  (function()
    {
    if ('number' == typeof self.list.length) 
      {
      for (var $index = 0, $$l = self.list.length; $index < $$l; $index++)
        {
        var item = self.list[$index];
        buf.push('<li');
        buf.push(attrs2({ "class": ('item') }, {}));
        buf.push('>');
        var __val__ = item
        buf.push(null == __val__ ? "" : __val__);
        buf.push('</li>');
        }
      }
    else 
      {
      for (var $index in self.list)
        {
        if (self.list.hasOwnProperty($index))
          {
          var item = self.list[$index];

          buf.push('<li');
          buf.push(attrs2({ "class": ('item') }, {}));
          buf.push('>');
          var __val__ = item
          buf.push(null == __val__ ? "" : __val__);
          buf.push('</li>');
          }
        }
      }
  }).call(this);
  buf.push('</ul></div>');return new Buffer(buf.join(""));
  }

jt6 = function ()
  {
  //var attrs = jade.attrs, escape = jade.escape, rethrow = jade.rethrow;
  //var self = locals || {};
  var __val__;
  s ='<div><h1' + attrs2({ "class": ('header') }, {}) + '>'
    + (null == (__val__ = self.header) ? "" : __val__) + '</h1><h2' + ({ "class": ('header2') }, {}) + '>'
    + (null == (__val__ = self.header2) ? "" : __val__) + '</h2><h3' + attrs2({ "class": ('header3') }, {}) + '>'
    + (null == (__val__ = self.header3) ? "" : __val__) + '</h3><h4' + attrs2({ "class": ('header4') }, {}) + '>'
    + (null == (__val__ = self.header4) ? "" : __val__) + '</h4><h5' + attrs2({ "class": ('header5') }, {}) + '>'
    + (null == (__val__ = self.header5) ? "" : __val__) + '</h5><h6' + attrs2({ "class": ('header6') }, {}) + '>'
    + (null == (__val__ = self.header6) ? "" : __val__) + '</h6><ul' + attrs2({ "class": ('list') }, {}) + '>';
  // iterate self.list
  (function()
    {
    var __val__;
    if ('number' == typeof self.list.length) 
      {
      for (var $index = 0, $$l = self.list.length; $index < $$l; $index++)
        {
        var item = self.list[$index];
        s += '<li' + attrs2({ "class": ('item') }, {}) + '>' + (null == (__val__ = item) ? "" : __val__) + '</li>';
        }
      }
    else 
      {
      for (var $index in self.list)
        {
        if (self.list.hasOwnProperty($index))
          {
          var item = self.list[$index];
          s += '<li' + attrs2({ "class": ('item') }, {}) + '>' + (null == (__val__ = item) ? "" : __val__) + '</li>';
          }
        }
      }
  }).call(this);
  s += '</ul></div>';
  return new Buffer(s);
  }


var Benchmark = require('benchmark')
var suite = new Benchmark.Suite

suite
.add('jt1 - (b.push())', jt1)
.add('jt2 - (+= & +)  ', jt2)
.add('jt3 - (+= only) ', jt3)
.add('jt4 - (+=, +, old attrs) ', jt4)
.add('jt5 - (b.push(), attrs2()) ', jt5)
.add('jt6 - (mostly +, attrs2()) ', jt6)
.on('cycle', function (event, bench) {
  console.log(bench.toString());
})
.on('complete', function () {
  console.log('Fastest is ' + this.filter('fastest').pluck('name'))
})
.run();

My tests show that substr is slower. See this.

Good thing I came back to write 'probably' :)

However, do you think it's too sloppy to just leave that extra space at the end? I'll benchmark your attrs with mine to see if there's a significant difference. If not, then yours is preferable as it leaves cleaner HTML.

I thought that maybe because it possibly used the same character buffer for the new substring it would just be a matter of creating a new String object, hence it would be a fast operation. Maybe it does a copy operation to form the substring, collapsing the internal linked list.

I think you'll need to have correct html that passes all the jade tests.