Playing Around with KaTex

See the Pen KaTex Superformula by Zevan Rosser (@ZevanRosser) on CodePen.

JavaScript Framework Thoughts Part 3

Today I had a chance to write the first proof of concept for the templating idea mentioned in part 2 of this post series. Really didn’t expect to get it working so quick but here it is:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <title></title>
    <script src="http://code.jquery.com/jquery-latest.min.js"></script>
    <script src="obj.js"></script>
    <script>
      $(function(){
 
        var data = {
          title : 'cool',
          titleStyle : 'color : red',
          some : { 
            nested : {
              prop : 'you got it'
            }
          },
          checked : false,
          items : [
            {value : 1},
            {value : 2},
            {value : 3}
          ], 
          files : [
            {id : 123, fileName : 'one'},
            {id : 321, fileName : 'two'},
            {id : 111, fileName : 'three'},
            {id : 222, fileName : 'four'}
          ],
          names : [
            'joe',
            'moe',
            'abe'
          ],
          collection : [
            { title : 'first', 
              things : [
                {thing : 'thing 1'},
                {thing : 'thing 2'},
                {thing : 'thing 3'}
              ]
             },
            { title : 'second', 
              things : [
                {thing : 'thing a'},
                {thing : 'thing b'},
                {thing : 'thing c'}
              ]
             }
          ]
        };
 
 
        var Template = function(html, data) {
          var div = document.createElement('div');
 
          this.isVar = /\s?^\*+/;
          this.isCollection = /^data/;
 
          div.innerHTML = html;
 
          this.traverse(div, data);
 
          document.body.appendChild(div);
        };
 
        Template.prototype = {
          constructor : Template,
          resolveVar : function(path, ctx, index){
            var curr;
            if (path === '*'){
              return ctx;
            }else{ 
              path = path.replace(/^\*/,'').split('.');
              curr = ctx;
 
              for (var i = 0; i < path.length; i++){
                curr = curr[path[i]];
              }
 
              if (curr) {
                return curr;
              } else {
                return false;
              }
            }
          },
 
          traverse : function(parent, scope, index, noChildren){
            var i, j, k, attr, val, varValue, node, tempEl, 
                oldScope, newScope, collection, newHTML, collectionItem;
 
            if (parent.attributes) {
              for (i = 0; i < parent.attributes.length; i++){
                attr = parent.attributes[i];
                if (attr.nodeValue.match(this.isVar)){
                  val = this.resolveVar(attr.nodeValue, scope, index); 
                  if (val === false || val === ''){
                    parent.attributes.removeNamedItem('checked');
                  } else {
                    parent.setAttribute(attr.name, this.resolveVar(attr.nodeValue, scope, index));
                  }
                }
              }
            }
 
            if (!parent.innerHTML) { return; }
 
            if (parent.innerHTML.match(this.isVar)){
              varValue = this.resolveVar(parent.innerHTML, scope, index);
              if (varValue){
                parent.innerHTML = varValue; 
              } 
            }
 
            for (var i = 0; i < parent.childNodes.length; i++){
              node = parent.childNodes[i];
 
              if (node.attributes){
                for(j = 0; j < node.attributes.length; j++){
                  attr = node.attributes[j];
                  if (attr.name.match(this.isCollection)){
 
                    tempEl = document.createElement('div');
                    tempEl.innerHTML = node.innerHTML;
                    oldScope = scope;
                    newScope = attr.name.replace('data-','');
                    collection = scope[newScope];
 
                    if (collection){
                      newHTML = "";
                      node.innerHTML = "";
                      for (var k = 0; k < collection.length; k++){
                        collectionItem = document.createElement('div');
                        collectionItem.innerHTML = tempEl.innerHTML;
 
                        this.traverse(collectionItem, collection[k], k); 
                        newHTML += collectionItem.innerHTML;
                      } 
                      node.innerHTML = newHTML;
                    } 
                    scope = oldScope;
                  }
                } 
 
              }
 
              if (node.childNodes.length > 0) {  
                if (node.nodeType === 3){ return; }
                this.traverse(node, scope, index);
              } else {
                this.traverse(node, scope, index, noChildren);
              }
            }
          }
        };
 
        var template = new Template($('#tmpl').html(), data);
 
      });
    </script>
    <style>
      body,html{
        font-family : sans-serif; 
      }
      .thing{
        border : 1px solid red; 
        padding : 5px;
      }
    </style>
  </head>
  <body> 
    <script id="tmpl" type="text/html">
      <div class="app">
 
        <h2 style="*titleStyle">*title</h2>
 
        <p>*some.nested.prop</p>
 
        <form>
          <input type="checkbox" checked="*checked">
        </form>
 
        <ul data-items>
          <li>*value</li>
        </ul>
 
        <h3>Files:</h3><hr>
        <select data-files>
          <option value="*id">*fileName</option>
        </select>
 
        <h3>Names:</h3><hr>
        <div data-names>
          <b>*</b>
          <div class="name">*</div>
        </div>
 
        <h3>Things:</h3><hr>
        <div data-collection>
          <div class='thing'>
            <h2>*title</h2>
            <div data-things>
              <p>*thing</p>
            </div>
          </div>
        </div>
 
      </div> 
    </script>
  </body>
</html>

So this takes data like this:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
var data = {
  title : 'cool',
  titleStyle : 'color : red',
  some : { 
    nested : {
      prop : 'you got it'
    }
  },
  checked : false,
  items : [
    {value : 1},
    {value : 2},
    {value : 3}
  ], 
  files : [
    {id : 123, fileName : 'one'},
    {id : 321, fileName : 'two'},
    {id : 111, fileName : 'three'},
    {id : 222, fileName : 'four'}
  ],
  names : [
    'joe',
    'moe',
    'abe'
  ],
  collection : [
    { title : 'first', 
      things : [
        {thing : 'thing 1'},
        {thing : 'thing 2'},
        {thing : 'thing 3'}
      ]
     },
    { title : 'second', 
      things : [
        {thing : 'thing a'},
        {thing : 'thing b'},
        {thing : 'thing c'}
      ]
     }
  ]
};

and a template like this:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
<div class="app">
  <h2 style="*titleStyle">*title</h2>
 
  <p>*some.nested.prop</p>
 
  <form>
    <input type="checkbox" checked="*checked">
  </form>
 
  <ul data-items>
    <li>*value</li>
  </ul>
 
  <h3>Files:</h3><hr>
  <select data-files>
    <option value="*id">*fileName</option>
  </select>
 
  <h3>Names:</h3><hr>
  <div data-names>
    <b>*</b>
    <div class="name">*</div>
  </div>
 
  <h3>Things:</h3><hr>
  <div data-collection>
    <div class='thing'>
      <h2>*title</h2>
      <div data-things>
        <p>*thing</p>
      </div>
    </div>
  </div>
 
</div>

and renders like this:

See the Pen mydVay by Zevan Rosser (@ZevanRosser) on CodePen.

The real trick here is the collections, that is, when the data has an array of objects this takes the existing nodes out of the element that needs to be the parent of a collection of elements, duplicates it and fills in the values as it goes.

This code needs some refactoring and possibly the addition of document fragments to speed it up a bit. Also there are a couple things that need to be figured out in terms of flexibility of the templates. Like, is it ok to do:

<h2>*variableA is a weird *variableB</h2>

This can get kind of hairy so I might just avoid it, forcing only vars and spaces to be able to be defined inside nodeValues… not sure yet…

<h2>*variableA *variableB</h2>

Next step is to combine this with the Watch class from Part 1 of this post series.

Yes