281 lines
9.8 KiB
Markdown
281 lines
9.8 KiB
Markdown
# depd
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[![NPM Version][npm-version-image]][npm-url]
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[![NPM Downloads][npm-downloads-image]][npm-url]
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[![Node.js Version][node-image]][node-url]
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[![Linux Build][travis-image]][travis-url]
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[![Windows Build][appveyor-image]][appveyor-url]
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[![Coverage Status][coveralls-image]][coveralls-url]
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Deprecate all the things
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> With great modules comes great responsibility; mark things deprecated!
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## Install
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This module is installed directly using `npm`:
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```sh
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$ npm install depd
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```
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This module can also be bundled with systems like
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[Browserify](http://browserify.org/) or [webpack](https://webpack.github.io/),
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though by default this module will alter it's API to no longer display or
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track deprecations.
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## API
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<!-- eslint-disable no-unused-vars -->
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```js
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var deprecate = require('depd')('my-module')
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```
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This library allows you to display deprecation messages to your users.
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This library goes above and beyond with deprecation warnings by
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introspection of the call stack (but only the bits that it is interested
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in).
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Instead of just warning on the first invocation of a deprecated
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function and never again, this module will warn on the first invocation
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of a deprecated function per unique call site, making it ideal to alert
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users of all deprecated uses across the code base, rather than just
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whatever happens to execute first.
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The deprecation warnings from this module also include the file and line
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information for the call into the module that the deprecated function was
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in.
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**NOTE** this library has a similar interface to the `debug` module, and
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this module uses the calling file to get the boundary for the call stacks,
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so you should always create a new `deprecate` object in each file and not
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within some central file.
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### depd(namespace)
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Create a new deprecate function that uses the given namespace name in the
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messages and will display the call site prior to the stack entering the
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file this function was called from. It is highly suggested you use the
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name of your module as the namespace.
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### deprecate(message)
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Call this function from deprecated code to display a deprecation message.
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This message will appear once per unique caller site. Caller site is the
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first call site in the stack in a different file from the caller of this
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function.
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If the message is omitted, a message is generated for you based on the site
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of the `deprecate()` call and will display the name of the function called,
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similar to the name displayed in a stack trace.
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### deprecate.function(fn, message)
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Call this function to wrap a given function in a deprecation message on any
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call to the function. An optional message can be supplied to provide a custom
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message.
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### deprecate.property(obj, prop, message)
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Call this function to wrap a given property on object in a deprecation message
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on any accessing or setting of the property. An optional message can be supplied
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to provide a custom message.
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The method must be called on the object where the property belongs (not
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inherited from the prototype).
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If the property is a data descriptor, it will be converted to an accessor
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descriptor in order to display the deprecation message.
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### process.on('deprecation', fn)
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This module will allow easy capturing of deprecation errors by emitting the
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errors as the type "deprecation" on the global `process`. If there are no
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listeners for this type, the errors are written to STDERR as normal, but if
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there are any listeners, nothing will be written to STDERR and instead only
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emitted. From there, you can write the errors in a different format or to a
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logging source.
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The error represents the deprecation and is emitted only once with the same
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rules as writing to STDERR. The error has the following properties:
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- `message` - This is the message given by the library
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- `name` - This is always `'DeprecationError'`
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- `namespace` - This is the namespace the deprecation came from
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- `stack` - This is the stack of the call to the deprecated thing
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Example `error.stack` output:
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```
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DeprecationError: my-cool-module deprecated oldfunction
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at Object.<anonymous> ([eval]-wrapper:6:22)
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at Module._compile (module.js:456:26)
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at evalScript (node.js:532:25)
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at startup (node.js:80:7)
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at node.js:902:3
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```
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### process.env.NO_DEPRECATION
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As a user of modules that are deprecated, the environment variable `NO_DEPRECATION`
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is provided as a quick solution to silencing deprecation warnings from being
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output. The format of this is similar to that of `DEBUG`:
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```sh
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$ NO_DEPRECATION=my-module,othermod node app.js
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```
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This will suppress deprecations from being output for "my-module" and "othermod".
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The value is a list of comma-separated namespaces. To suppress every warning
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across all namespaces, use the value `*` for a namespace.
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Providing the argument `--no-deprecation` to the `node` executable will suppress
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all deprecations (only available in Node.js 0.8 or higher).
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**NOTE** This will not suppress the deperecations given to any "deprecation"
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event listeners, just the output to STDERR.
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### process.env.TRACE_DEPRECATION
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As a user of modules that are deprecated, the environment variable `TRACE_DEPRECATION`
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is provided as a solution to getting more detailed location information in deprecation
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warnings by including the entire stack trace. The format of this is the same as
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`NO_DEPRECATION`:
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```sh
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$ TRACE_DEPRECATION=my-module,othermod node app.js
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```
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This will include stack traces for deprecations being output for "my-module" and
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"othermod". The value is a list of comma-separated namespaces. To trace every
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warning across all namespaces, use the value `*` for a namespace.
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Providing the argument `--trace-deprecation` to the `node` executable will trace
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all deprecations (only available in Node.js 0.8 or higher).
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**NOTE** This will not trace the deperecations silenced by `NO_DEPRECATION`.
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## Display
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When a user calls a function in your library that you mark deprecated, they
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will see the following written to STDERR (in the given colors, similar colors
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and layout to the `debug` module):
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```
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bright cyan bright yellow
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| | reset cyan
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▼ ▼ ▼ ▼
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my-cool-module deprecated oldfunction [eval]-wrapper:6:22
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▲ ▲ ▲ ▲
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namespace | | location of mycoolmod.oldfunction() call
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| deprecation message
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the word "deprecated"
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```
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If the user redirects their STDERR to a file or somewhere that does not support
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colors, they see (similar layout to the `debug` module):
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```
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Sun, 15 Jun 2014 05:21:37 GMT my-cool-module deprecated oldfunction at [eval]-wrapper:6:22
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▲ ▲ ▲ ▲ ▲
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timestamp of message namespace | | location of mycoolmod.oldfunction() call
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| deprecation message
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the word "deprecated"
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```
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## Examples
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### Deprecating all calls to a function
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This will display a deprecated message about "oldfunction" being deprecated
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from "my-module" on STDERR.
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```js
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var deprecate = require('depd')('my-cool-module')
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// message automatically derived from function name
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// Object.oldfunction
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exports.oldfunction = deprecate.function(function oldfunction () {
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// all calls to function are deprecated
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})
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// specific message
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exports.oldfunction = deprecate.function(function () {
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// all calls to function are deprecated
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}, 'oldfunction')
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```
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### Conditionally deprecating a function call
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This will display a deprecated message about "weirdfunction" being deprecated
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from "my-module" on STDERR when called with less than 2 arguments.
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```js
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var deprecate = require('depd')('my-cool-module')
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exports.weirdfunction = function () {
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if (arguments.length < 2) {
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// calls with 0 or 1 args are deprecated
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deprecate('weirdfunction args < 2')
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}
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}
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```
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When calling `deprecate` as a function, the warning is counted per call site
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within your own module, so you can display different deprecations depending
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on different situations and the users will still get all the warnings:
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```js
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var deprecate = require('depd')('my-cool-module')
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exports.weirdfunction = function () {
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if (arguments.length < 2) {
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// calls with 0 or 1 args are deprecated
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deprecate('weirdfunction args < 2')
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} else if (typeof arguments[0] !== 'string') {
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// calls with non-string first argument are deprecated
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deprecate('weirdfunction non-string first arg')
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}
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}
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```
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### Deprecating property access
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This will display a deprecated message about "oldprop" being deprecated
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from "my-module" on STDERR when accessed. A deprecation will be displayed
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when setting the value and when getting the value.
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```js
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var deprecate = require('depd')('my-cool-module')
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exports.oldprop = 'something'
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// message automatically derives from property name
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deprecate.property(exports, 'oldprop')
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// explicit message
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deprecate.property(exports, 'oldprop', 'oldprop >= 0.10')
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```
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## License
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[MIT](LICENSE)
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[appveyor-image]: https://badgen.net/appveyor/ci/dougwilson/nodejs-depd/master?label=windows
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[appveyor-url]: https://ci.appveyor.com/project/dougwilson/nodejs-depd
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[coveralls-image]: https://badgen.net/coveralls/c/github/dougwilson/nodejs-depd/master
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[coveralls-url]: https://coveralls.io/r/dougwilson/nodejs-depd?branch=master
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[node-image]: https://badgen.net/npm/node/depd
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[node-url]: https://nodejs.org/en/download/
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[npm-downloads-image]: https://badgen.net/npm/dm/depd
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[npm-url]: https://npmjs.org/package/depd
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[npm-version-image]: https://badgen.net/npm/v/depd
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[travis-image]: https://badgen.net/travis/dougwilson/nodejs-depd/master?label=linux
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[travis-url]: https://travis-ci.org/dougwilson/nodejs-depd
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