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10 Deprecate all the things
12 > With great modules comes great responsibility; mark things deprecated!
23 var deprecate = require('depd')('my-module')
26 This library allows you to display deprecation messages to your users.
27 This library goes above and beyond with deprecation warnings by
28 introspection of the call stack (but only the bits that it is interested
31 Instead of just warning on the first invocation of a deprecated
32 function and never again, this module will warn on the first invocation
33 of a deprecated function per unique call site, making it ideal to alert
34 users of all deprecated uses across the code base, rather than just
35 whatever happens to execute first.
37 The deprecation warnings from this module also include the file and line
38 information for the call into the module that the deprecated function was
41 **NOTE** this library has a similar interface to the `debug` module, and
42 this module uses the calling file to get the boundary for the call stacks,
43 so you should always create a new `deprecate` object in each file and not
44 within some central file.
48 Create a new deprecate function that uses the given namespace name in the
49 messages and will display the call site prior to the stack entering the
50 file this function was called from. It is highly suggested you use the
51 name of your module as the namespace.
53 ### deprecate(message)
55 Call this function from deprecated code to display a deprecation message.
56 This message will appear once per unique caller site. Caller site is the
57 first call site in the stack in a different file from the caller of this
60 If the message is omitted, a message is generated for you based on the site
61 of the `deprecate()` call and will display the name of the function called,
62 similar to the name displayed in a stack trace.
64 ### deprecate.function(fn, message)
66 Call this function to wrap a given function in a deprecation message on any
67 call to the function. An optional message can be supplied to provide a custom
70 ### deprecate.property(obj, prop, message)
72 Call this function to wrap a given property on object in a deprecation message
73 on any accessing or setting of the property. An optional message can be supplied
74 to provide a custom message.
76 The method must be called on the object where the property belongs (not
77 inherited from the prototype).
79 If the property is a data descriptor, it will be converted to an accessor
80 descriptor in order to display the deprecation message.
82 ### process.on('deprecation', fn)
84 This module will allow easy capturing of deprecation errors by emitting the
85 errors as the type "deprecation" on the global `process`. If there are no
86 listeners for this type, the errors are written to STDERR as normal, but if
87 there are any listeners, nothing will be written to STDERR and instead only
88 emitted. From there, you can write the errors in a different format or to a
91 The error represents the deprecation and is emitted only once with the same
92 rules as writing to STDERR. The error has the following properties:
94 - `message` - This is the message given by the library
95 - `name` - This is always `'DeprecationError'`
96 - `namespace` - This is the namespace the deprecation came from
97 - `stack` - This is the stack of the call to the deprecated thing
99 Example `error.stack` output:
102 DeprecationError: my-cool-module deprecated oldfunction
103 at Object.<anonymous> ([eval]-wrapper:6:22)
104 at Module._compile (module.js:456:26)
105 at evalScript (node.js:532:25)
106 at startup (node.js:80:7)
110 ### process.env.NO_DEPRECATION
112 As a user of modules that are deprecated, the environment variable `NO_DEPRECATION`
113 is provided as a quick solution to silencing deprecation warnings from being
114 output. The format of this is similar to that of `DEBUG`:
117 $ NO_DEPRECATION=my-module,othermod node app.js
120 This will suppress deprecations from being output for "my-module" and "othermod".
121 The value is a list of comma-separated namespaces. To suppress every warning
122 across all namespaces, use the value `*` for a namespace.
124 Providing the argument `--no-deprecation` to the `node` executable will suppress
125 all deprecations (only available in Node.js 0.8 or higher).
127 **NOTE** This will not suppress the deperecations given to any "deprecation"
128 event listeners, just the output to STDERR.
130 ### process.env.TRACE_DEPRECATION
132 As a user of modules that are deprecated, the environment variable `TRACE_DEPRECATION`
133 is provided as a solution to getting more detailed location information in deprecation
134 warnings by including the entire stack trace. The format of this is the same as
138 $ TRACE_DEPRECATION=my-module,othermod node app.js
141 This will include stack traces for deprecations being output for "my-module" and
142 "othermod". The value is a list of comma-separated namespaces. To trace every
143 warning across all namespaces, use the value `*` for a namespace.
145 Providing the argument `--trace-deprecation` to the `node` executable will trace
146 all deprecations (only available in Node.js 0.8 or higher).
148 **NOTE** This will not trace the deperecations silenced by `NO_DEPRECATION`.
152 ![message](files/message.png)
154 When a user calls a function in your library that you mark deprecated, they
155 will see the following written to STDERR (in the given colors, similar colors
156 and layout to the `debug` module):
159 bright cyan bright yellow
163 my-cool-module deprecated oldfunction [eval]-wrapper:6:22
166 namespace | | location of mycoolmod.oldfunction() call
167 | deprecation message
168 the word "deprecated"
171 If the user redirects their STDERR to a file or somewhere that does not support
172 colors, they see (similar layout to the `debug` module):
175 Sun, 15 Jun 2014 05:21:37 GMT my-cool-module deprecated oldfunction at [eval]-wrapper:6:22
178 timestamp of message namespace | | location of mycoolmod.oldfunction() call
179 | deprecation message
180 the word "deprecated"
185 ### Deprecating all calls to a function
187 This will display a deprecated message about "oldfunction" being deprecated
188 from "my-module" on STDERR.
191 var deprecate = require('depd')('my-cool-module')
193 // message automatically derived from function name
194 // Object.oldfunction
195 exports.oldfunction = deprecate.function(function oldfunction() {
196 // all calls to function are deprecated
200 exports.oldfunction = deprecate.function(function () {
201 // all calls to function are deprecated
205 ### Conditionally deprecating a function call
207 This will display a deprecated message about "weirdfunction" being deprecated
208 from "my-module" on STDERR when called with less than 2 arguments.
211 var deprecate = require('depd')('my-cool-module')
213 exports.weirdfunction = function () {
214 if (arguments.length < 2) {
215 // calls with 0 or 1 args are deprecated
216 deprecate('weirdfunction args < 2')
221 When calling `deprecate` as a function, the warning is counted per call site
222 within your own module, so you can display different deprecations depending
223 on different situations and the users will still get all the warnings:
226 var deprecate = require('depd')('my-cool-module')
228 exports.weirdfunction = function () {
229 if (arguments.length < 2) {
230 // calls with 0 or 1 args are deprecated
231 deprecate('weirdfunction args < 2')
232 } else if (typeof arguments[0] !== 'string') {
233 // calls with non-string first argument are deprecated
234 deprecate('weirdfunction non-string first arg')
239 ### Deprecating property access
241 This will display a deprecated message about "oldprop" being deprecated
242 from "my-module" on STDERR when accessed. A deprecation will be displayed
243 when setting the value and when getting the value.
246 var deprecate = require('depd')('my-cool-module')
248 exports.oldprop = 'something'
250 // message automatically derives from property name
251 deprecate.property(exports, 'oldprop')
254 deprecate.property(exports, 'oldprop', 'oldprop >= 0.10')
261 [npm-version-image]: https://img.shields.io/npm/v/depd.svg?style=flat
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263 [npm-url]: https://npmjs.org/package/depd
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265 [travis-url]: https://travis-ci.org/dougwilson/nodejs-depd
266 [coveralls-image]: https://img.shields.io/coveralls/dougwilson/nodejs-depd.svg?style=flat
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