Replace transferPropsTo with transferring props patterns

Author: sebmarkbage

docs/docs/02.2-jsx-spread.md

@@ -68,4 +68,4 @@ Merging two objects can be expressed as:
 
 > Note:
 >
-> Activate experimental syntax by using the [JSX command-line tool](http://npmjs.org/package/react-tools) with the `--harmony` flag.
+> Use the [JSX command-line tool](http://npmjs.org/package/react-tools) with the `--harmony` flag to activate the experimental ES7 syntax.

docs/docs/05-reusable-components.md

@@ -3,7 +3,7 @@ id: reusable-components
 title: Reusable Components
 permalink: reusable-components.html
 prev: multiple-components.html
-next: forms.html
+next: transferring-props.html
 ---
 
 When designing interfaces, break down the common design elements (buttons, form fields, layout components, etc) into reusable components with well-defined interfaces. That way, the next time you need to build some UI you can write much less code, which means faster development time, fewer bugs, and fewer bytes down the wire.

docs/docs/06-transferring-props.md

@@ -0,0 +1,159 @@
+---
+id: transferring-props
+title: Transferring Props
+permalink: transferring-props.html
+prev: reusable-components.html
+next: forms.html
+---
+
+It's a common pattern in React to wrap a component in an abstraction. The outer component exposes a simple property to do something that might have more complex implementation details.
+
+You can use [JSX spread attributes](/react/docs/jsx-spread.html) to merge the old props with additional values:
+
+```javascript
+return <Component {...this.props} more="values" />;
+```
+
+If you don't use JSX, you can use any object helper such as ES6 `Object.assign` or Underscore `_.extend`:
+
+```javascript
+return Component(Object.assign({}, this.props, { more: 'values' }));
+```
+
+The rest of this tutorial explains best practices. It uses JSX and experimental ES7 syntax.
+
+## Manual Transfer
+
+Most of the time you should explicitly pass the properties down. That ensures that you only exposes a subset of the inner API, one that you know will work.
+
+```javascript
+var FancyCheckbox = React.createClass({
+ render: function() {
+ var fancyClass = this.props.checked ? 'FancyChecked' : 'FancyUnchecked';
+ return (
+ <div className={fancyClass} onClick={this.props.onClick}>
+ {this.props.children}
+ </div>
+ );
+ }
+});
+React.renderComponent(
+ <FancyCheckbox checked={true} onClick={console.log}>
+ Hello world!
+ </FancyCheckbox>,
+ document.body
+);
+```
+
+But what about the `name` prop? Or the `title` prop? Or `onMouseOver`?
+
+## Transferring with `...` in JSX
+
+Sometimes it's fragile and tedious to pass every property along. In that case you can use [destructuring assignment](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment) with rest properties to extract a set of unknown properties.
+
+List out all the properties that you would like to consume, followed by `...other`.
+
+```javascript
+var { checked, ...other } = this.props;
+```
+
+This ensures that you pass down all the props EXCEPT the ones you're consuming yourself.
+
+```javascript
+var FancyCheckbox = React.createClass({
+ render: function() {
+ var { checked, ...other } = this.props;
+ var fancyClass = checked ? 'FancyChecked' : 'FancyUnchecked';
+ // `other` contains { onClick: console.log } but not the checked property
+ return (
+ <div {...other} className={fancyClass} />
+ );
+ }
+});
+React.renderComponent(
+ <FancyCheckbox checked={true} onClick={console.log}>
+ Hello world!
+ </FancyCheckbox>,
+ document.body
+);
+```
+
+> NOTE:
+> 
+> In the example above, the `checked` prop is also a valid DOM attribute. If you didn't use destructuring in this way you might inadvertently pass it along.
+
+Always use the destructuring pattern when transferring unknown `other` props.
+
+```javascript
+var FancyCheckbox = React.createClass({
+ render: function() {
+ var fancyClass = this.props.checked ? 'FancyChecked' : 'FancyUnchecked';
+ // ANTI-PATTERN: `checked` would be passed down to the inner component
+ return (
+ <div {...this.props} className={fancyClass} />
+ );
+ }
+});
+```
+
+## Consuming and Transferring the Same Prop
+
+If your component wants to consume a property but also pass it along, you can repass it explicitly `checked={checked}`. This is preferable to passing the full `this.props` object since it's easier to refactor and lint.
+
+```javascript
+var FancyCheckbox = React.createClass({
+ render: function() {
+ var { checked, title, ...other } = this.props;
+ var fancyClass = checked ? 'FancyChecked' : 'FancyUnchecked';
+ var fancyTitle = checked ? 'X ' + title : 'O ' + title;
+ return (
+ <label>
+ <input {...other}
+ checked={checked}
+ className={fancyClass}
+ type="checkbox"
+ />
+ {fancyTitle}
+ </label>
+ );
+ }
+});
+```
+
+> NOTE:
+> 
+> Order matters. By putting the `{...other}` before your JSX props you ensure that the consumer of your component can't override them. In the example above we have guaranteed that the input will be of type `"checkbox"`.
+
+## Rest and Spread Properties `...`
+
+Rest properties allow you to extract the remaining properties from an object into a new object. It excludes every other property listed in the destructuring pattern.
+
+This is an experimental implementation of an [ES7 proposal](https://github.com/sebmarkbage/ecmascript-rest-spread).
+
+```javascript
+var { x, y, ...z } = { x: 1, y: 2, a: 3, b: 4 };
+x; // 1
+y; // 2
+z; // { a: 3, b: 4 }
+```
+
+> Note:
+>
+> Use the [JSX command-line tool](http://npmjs.org/package/react-tools) with the `--harmony` flag to activate the experimental ES7 syntax.
+
+## Transferring with Underscore
+
+If you don't use JSX, you can use a library to achieve the same pattern. Underscore supports `_.omit` to filter out properties and `_.extend` to copy properties onto a new object.
+
+```javascript
+var FancyCheckbox = React.createClass({
+ render: function() {
+ var checked = this.props.checked;
+ var other = _.omit(this.props, 'checked');
+ var fancyClass = checked ? 'FancyChecked' : 'FancyUnchecked';
+ return (
+ React.DOM.div(_.extend({}, other, { className: fancyClass }))
+ );
+ }
+});
+```

docs/docs/06-forms.md renamed to docs/docs/07-forms.md

@@ -2,7 +2,7 @@
 id: forms
 title: Forms
 permalink: forms.html
-prev: reusable-components.html
+prev: transferring-props.html
 next: working-with-the-browser.html
 ---