152 lines
3.3 KiB
Markdown
152 lines
3.3 KiB
Markdown
# prop(attrName, callback)
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- [Description](#description)
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- [Signature](#signature)
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- [How it works](#how-it-works)
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- [Sending through requests](#sending-through-requests)
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---
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### Description
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Returns a simple getter/setter object.
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```javascript
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var name = m.prop("John")
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var oldName = name.get() // First, it's set to "John"
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name.set("Mary") // Set the value to "Mary"
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var newName = name.get() // Now it's "Mary", not "John"
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```
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---
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### Signature
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`prop = m.prop(initial?)`
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Argument | Type | Required | Description
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----------- | ------ | -------- | ---
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`initial` | `any` | No | The prop's initial value
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**returns** | `Prop` | | A prop
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`value = prop.get()`
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Argument | Type | Required | Description
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----------- | ----- | -------- | ---
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**returns** | `any` | | The prop's current value
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`newValue = prop.set(newValue)`
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Argument | Type | Required | Description
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----------- | ----- | -------- | ---
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`newValue` | `any` | Yes | The value to set the prop to
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**returns** | `any` | | The value you just set the prop to, for convenience
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[How to read signatures](signatures.md)
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---
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### How it works
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The `m.prop` method creates a prop, a getter/setter object wrapping a single mutable reference. You can get the current value with `prop.get()` and set it with `prop.set(value)`. Unlike [streams](stream.md), you can't observe them, so you can't do as much with them.
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In conjunction with [`m.withAttr`](withAttr.md), you can emulate two-way binding pretty easily.
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```javascript
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var Component = {
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oninit: function(vnode) {
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vnode.state.current = m.prop("")
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},
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view: function(vnode) {
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return m("input", {
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oninput: m.withAttr("value", vnode.state.current.set),
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value: vnode.state.current.get(),
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})
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}
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}
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```
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They're also useful for making simpler models.
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```javascript
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// With props
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var Auth = {
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username: m.prop(""),
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password: m.prop(""),
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canSubmit: function() {
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return Auth.username.get() !== "" && Auth.password.get() !== ""
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},
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login: function() {
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// ...
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},
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}
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// Without props
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var Auth = {
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username: "",
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password: "",
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setUsername: function(value) {
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Auth.username = value
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}
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setPassword: function(value) {
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Auth.password = value
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}
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canSubmit: function() {
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return Auth.username !== "" && Auth.password !== ""
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},
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login: function() {
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// ...
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},
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}
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```
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---
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### Sending through requests
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For convenience, props define `.toJSON` as an alias for `.get`. This is so you can send them through `m.request` without serializing them manually.
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We could also take this model and simplify it:
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```javascript
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// How it's loaded
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User.load = function(id) {
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return m.request({
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method: "GET",
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url: "https://rem-rest-api.herokuapp.com/api/users/" + id,
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withCredentials: true,
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})
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.then(function(result) {
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User.current = {
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id: result.id,
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firstName: m.prop(result.firstName),
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lastName: m.prop(result.lastName),
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}
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})
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}
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// Original
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User.save = function(user) {
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return m.request({
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method: "PUT",
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url: "https://rem-rest-api.herokuapp.com/api/users/" + user.id,
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data: {
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id: user.id,
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firstName: user.firstName.get(),
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lastName: user.lastName.get(),
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},
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withCredentials: true,
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})
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}
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// Simplified
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User.save = function(user) {
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return m.request({
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method: "PUT",
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url: "https://rem-rest-api.herokuapp.com/api/users/" + user.id,
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data: user,
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withCredentials: true,
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})
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}
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```
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