preload-webpack-plugin/src/lib/insert-links-into-html.js at 0e642093eeaee227bd30d6f3144b89f16af2125f · GoogleChromeLabs/preload-webpack-plugin · GitHub

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
/**
 * @license
 * Copyright 2018 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

function insertLinksIntoHtml({html, links=[], target}) {
  if (links.length === 0) {
    return html;
  }
  if (target === 'head') {
    if (html.includes('</head>')) {
      // If a valid closing </head> is found, insert the new <link>s right before it.
      return html.replace('</head>', `${links.join('')}</head>`);
    }

    if (html.includes('<body>')) {
      // If there's a <body> but no valid closing </head>, create a <head> containing the <link>s.
      return html.replace('<body>', `<head>${links.join('')}</head><body>`);
    }
    throw new Error(`The HTML provided did not contain a </head> or a <body>:\n\n${html}`);
  }

  if (target === 'body') {
    if (html.includes('</body>')) {
      // If a valid closing </body> is found, insert the new <link>s right before it.
      return html.replace('</body>', `${links.join('')}</body>`);
    }

    if (html.includes('</head>')) {
      // If there's a valid closing </head> but no valid closing <body>, create a <body> containing the <link>s.
      return html.replace('</head>', `</head><body>${links.join('')}</body>`);
    }
    throw new Error(`The HTML provided did not contain a </head> or a </body>:\n\n${html}`);
  }
}

module.exports = insertLinksIntoHtml;