| # debuglog - backport of util.debuglog() from node v0.11 |
| |
| To facilitate using the `util.debuglog()` function that will be available when |
| node v0.12 is released now, this is a copy extracted from the source. |
| |
| ## require('debuglog') |
| |
| Return `util.debuglog`, if it exists, otherwise it will return an internal copy |
| of the implementation from node v0.11. |
| |
| ## debuglog(section) |
| |
| * `section` {String} The section of the program to be debugged |
| * Returns: {Function} The logging function |
| |
| This is used to create a function which conditionally writes to stderr |
| based on the existence of a `NODE_DEBUG` environment variable. If the |
| `section` name appears in that environment variable, then the returned |
| function will be similar to `console.error()`. If not, then the |
| returned function is a no-op. |
| |
| For example: |
| |
| ```javascript |
| var debuglog = util.debuglog('foo'); |
| |
| var bar = 123; |
| debuglog('hello from foo [%d]', bar); |
| ``` |
| |
| If this program is run with `NODE_DEBUG=foo` in the environment, then |
| it will output something like: |
| |
| FOO 3245: hello from foo [123] |
| |
| where `3245` is the process id. If it is not run with that |
| environment variable set, then it will not print anything. |
| |
| You may separate multiple `NODE_DEBUG` environment variables with a |
| comma. For example, `NODE_DEBUG=fs,net,tls`. |
