132 lines
2.8 KiB
Markdown
132 lines
2.8 KiB
Markdown
# option-chain [](https://travis-ci.org/avajs/option-chain) [](https://coveralls.io/github/avajs/option-chain?branch=master)
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> Use fluent property chains in lieu of options objects
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## Install
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```
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$ npm install --save option-chain
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```
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## Usage
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```js
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const optionChain = require('option-chain');
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const optionDefinition = {
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defaults: {
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bar: false
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},
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chainableMethods: {
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foo: {foo: true},
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notFoo: {foo: false},
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bar: {bar: true}
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}
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};
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function printOptionsAndArgs(options, args) {
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console.log(options);
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if (args.length) {
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console.log(args);
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}
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}
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const fn = optionChain(optionDefinition, printOptionsAndArgs);
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fn();
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//=> [{bar: false}]
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fn.bar();
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//=> [{bar: true}]
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fn.foo.bar();
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//=> [{foo: true, bar: false}]
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fn.foo('a', 'b');
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//=> [{foo: true, bar: false}]
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//=> ['a', 'b']
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```
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## API
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### optionChain(options, callback, [target])
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#### options
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##### chainableMethods
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*Required*<br>
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Type: `Object`
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A map of chainable property names to the options set by adding property to the chain.
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Given the following:
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```js
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const chainableMethods = {
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foo: {foo: true},
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notFoo: {foo: false},
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bar: {bar: true},
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both: {foo: true, bar: true}
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}
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```
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Then:
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- `fn.foo` would set `foo` to `true`.
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- `fn.bar` would set `bar` to `true`.
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- `fn.both` sets both `foo` and `bar` to `true`.
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- The last property in the chain takes precedence, so `fn.foo.notFoo` would result in `foo` being `false`.
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##### defaults
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Type: `Object`<br>
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Default: `{}`
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A set of default starting properties.
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##### spread
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Type: `boolean`<br>
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Default: `false`
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By default, any arguments passed to the wrapper are passed as an array to the second argument of the wrapped function. When this is `true`, additional arguments will be spread out as additional arguments:
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```js
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function withoutSpread(opts, args) {
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let foo = args[0];
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let bar = args[1];
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// ...
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}
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function withSpread(opts, foo, bar) {
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// ...
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}
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```
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#### callback
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Type: `Function`
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This callback is called with the accumulated options as the first argument. Depending on the value of `options.spread`, arguments passed to the wrapper will either be an array as the second argument or spread out as the 2nd, 3rd, 4th... arguments.
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#### target
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If supplied, the `target` object is extended with the property getters and returned. Otherwise a wrapper function is created for `options.defaults`, then that wrapper is extended and returned.
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*Hint:* If you want to extend a `target` and add a method that simply uses the defaults, add a chainable method definition with an empty spec:
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```js
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const chainableMethods = {
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defaultMethodName: {}
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}
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```
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## License
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MIT © [James Talmage](https://github.com/jamestalmage)
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