summaryrefslogtreecommitdiffstats
path: root/remote/test/puppeteer/src/common/Debug.ts
blob: 425b7c305a46d0acf2360fc5e898377334d2d93c (plain)
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
/**
 * Copyright 2020 Google Inc. All rights reserved.
 *
 * 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.
 */

import {isNode} from '../environment.js';

declare global {
  // eslint-disable-next-line no-var
  var __PUPPETEER_DEBUG: string;
}

/**
 * @internal
 */
let debugModule: typeof import('debug') | null = null;
/**
 * @internal
 */
export async function importDebug(): Promise<typeof import('debug')> {
  if (!debugModule) {
    debugModule = (await import('debug')).default;
  }
  return debugModule;
}

/**
 * A debug function that can be used in any environment.
 *
 * @remarks
 * If used in Node, it falls back to the
 * {@link https://www.npmjs.com/package/debug | debug module}. In the browser it
 * uses `console.log`.
 *
 * In Node, use the `DEBUG` environment variable to control logging:
 *
 * ```
 * DEBUG=* // logs all channels
 * DEBUG=foo // logs the `foo` channel
 * DEBUG=foo* // logs any channels starting with `foo`
 * ```
 *
 * In the browser, set `window.__PUPPETEER_DEBUG` to a string:
 *
 * ```
 * window.__PUPPETEER_DEBUG='*'; // logs all channels
 * window.__PUPPETEER_DEBUG='foo'; // logs the `foo` channel
 * window.__PUPPETEER_DEBUG='foo*'; // logs any channels starting with `foo`
 * ```
 *
 * @example
 *
 * ```
 * const log = debug('Page');
 *
 * log('new page created')
 * // logs "Page: new page created"
 * ```
 *
 * @param prefix - this will be prefixed to each log.
 * @returns a function that can be called to log to that debug channel.
 *
 * @internal
 */
export const debug = (prefix: string): ((...args: unknown[]) => void) => {
  if (isNode) {
    return async (...logArgs: unknown[]) => {
      (await importDebug())(prefix)(logArgs);
    };
  }

  return (...logArgs: unknown[]): void => {
    const debugLevel = (globalThis as any).__PUPPETEER_DEBUG;
    if (!debugLevel) {
      return;
    }

    const everythingShouldBeLogged = debugLevel === '*';

    const prefixMatchesDebugLevel =
      everythingShouldBeLogged ||
      /**
       * If the debug level is `foo*`, that means we match any prefix that
       * starts with `foo`. If the level is `foo`, we match only the prefix
       * `foo`.
       */
      (debugLevel.endsWith('*')
        ? prefix.startsWith(debugLevel)
        : prefix === debugLevel);

    if (!prefixMatchesDebugLevel) {
      return;
    }

    // eslint-disable-next-line no-console
    console.log(`${prefix}:`, ...logArgs);
  };
};