Release 1.0.0 Evangelion · vuejs/vue

"The fate of destruction is also the joy of rebirth." - SEELE

About the Release

Please read the blog post.

Known Issues

v-for="(index, val) in items" syntax doesn't update the index properly. This has been fixed in dev branch and will be out in 1.0.1.

Upgrade Guide

General Tips

If you are familiar with 0.12. or upgrading an active app from 0.12:
1. Read through the notable changes below to get a general idea of the relatively big changes.
2. Read through the revised official guide. It is highly recommended to do this before you upgrade.
3. Upgrade to the 1.0.0 migration build first. The migration build is fully 0.12.16 compatible and also includes all the new features in 1.0.0. It also raises deprecation warnings for any usage of deprecated API.
4. Consult the full changelog and the updated API Reference as you work through the deprecation warnings. Once your app no longer raises any warnings using the migration build, it should work properly in 1.0.0.
If you are relatively new to Vue.js:
- Just go read the official guide!

Notable Changes

Template Syntax Change

This is the biggest change: directive syntax has been overhauled. No more multiple clauses; arguments are now placed inside the attribute name. The attribute value should now always be a single JavaScript expression followed by filters.
Strict Mode by Default

In the past, asset resolution (components, directives, filters...) has implicit fallback: if an asset is not found in the current component, Vue.js will recursively look for it in its parent, its parent's parent... and so on. This allows you to, say, define a component in the root instance and use it in any child component. It is convenient, however we've found that in large projects it results to implicit coupling between a child component and its ancestors. It also hurts maintainability - when you are looking at a child component in isolation, it's hard to identify where an asset comes from because it could've been provided by any ancestor up the component chain.

Therefore, in 1.0 all asset resolution is "strict": an asset should either be defined on the current component, or defined as a true global asset (using one of the global Vue.xxx asset registration methods).
Bye v-repeat, Hi v-for

v-repeat has been replaced by v-for, which is much faster, but comes with a few differences:
1. A alias is required now: so you should always do v-for="item in items", no more v-for="items".
2. The scoping is different when you use v-for on a component - it no longer automatically injects the data and meta properties like $index and $key into the component - you now need to explicitly pass them down using props. This makes the child component explicit about where its data comes from.
- Detailed Changes
- Docs
<slot> is the new <content>

The Web Components spec drafters are ditching the <content> API in favor of <slot>. Since Vue.js components are modeled after Web Components, and since the <slot> API does make things more explicit than relying on CSS selectors, we are moving to the <slot> API too.
- Reference
- Docs

Full Changelog (from 0.12.16)

Template Syntax Changes

Directive Arguments

The concept of multiple clauses (multiple directives separated by comma in the same attribute) is deprecated, and directive arguments are moved into the attribute name:

<!-- before: -->
<div v-dirname="arg1: expression1, arg2: expression2">

<!-- after: -->
<div
  v-dirname:arg1="expression1"
  v-dirname:arg2="expression2">

Using real directives as example:

<!-- before: -->
<div v-on="click: doThis, keyup: doThat">

<!-- after: -->
<div
  v-on:click="doThis"
  v-on:keyup="doThat">

Literal Directives

There is no longer "literal directives" from the implementation perspective. All directives are reactive by default, which makes it easy to know whether an attribute value is an expression or a literal string. If you wish to pass the directive a literal string, use the following syntax:
```

<div v-dirname="abc">


<div v-dirname.literal="abc">
```
The ending .literal is called a Binding Modifier, which forces the directive to be bound in literal mode. We will see this concept used below for prop binding types as well. In literal mode, the directive's update function will be called once, with the literal string as the argument.

Attribute Bindings

Mustache tags can only appear inside native attributes. To dynamically bind a custom attribute or a prop, use the v-bind directive (which replaces v-attr):

<!-- this is valid -->
<a href="{{baseURL}}/abc"></a>

<!-- these are no longer valid -->
<component is="{{view}}"></component>
<partial name="{{partialName}}"></partial>

<!-- use v-bind for non-native attributes -->
<component v-bind:is="view"></component>
<partial v-bind:name="partialName"></partial>

Vue will raise a warning whenever mustaches are used in non-native attributes.

Props

Previously props use mustaches to indicate reactivity. Now they must use v-bind:

<!-- before -->
<my-comp
  prop="a literal string"
  prop="{{expression}}">
<my-comp>

<my-comp
  prop="a literal string"
  v-bind:prop="expression">
</my-comp>

Binding type indicators (@ and *) are now replaced by more explicit binding modifiers:

<!-- before -->
<my-comp
  prop="{{defaultOneWay}}"
  prop="{{@twoWay}}"
  prop="{{*oneTime}}">
</my-comp>

<!-- after -->
<my-comp
  v-bind:prop="defaultOneWay"
  v-bind:prop.sync="twoWay"
  v-bind:prop.once="oneTime">
</my-comp>

Shorthands

You may have noticed we will be using v-bind and v-on quite a lot. 1.0 will provide optional shorthand syntax for these two directives. v-bind: can be shortened to a single colon :, while v-on: can be shortened to a single @ symbol:
```

<img :src="imgSrc">


<input @click="handleClick" @keyup="handleKeyup">


<my-comp
  :prop="expression"
  :prop.sync="twoWay"
  :prop.once="oneTime">
</my-comp>


<component :is="view"></component>
<partial :name="partialName"></partial>
```
If you are only using Vue as an enhancement on existing HTML pages, you may want to stick with the v- prefixed versions. The shorthand is designed to make the template more succinct when you are building large SPAs where Vue manages everything. Don't worry about it not looking like valid HTML - all browsers can parse it just fine, and Vue removes all the special stuff in the rendered HTML anyway.

Directive Changes

v-for

v-repeat has been deprecated in favor of v-for. Differences between v-for and v-repeat:
1. Required alias
  
  Alias is required when using v-for, and the item in items syntax is preferred. It reads more naturally:
```
<li v-for="item in items"></li>
```
  This also means the $value meta property will no longer be used. $index and $key are still available. You can also still refer to the parent scope index in nested loops as $parent.$index.
2. No more anonymous child VMs
  
  Previously, v-repeat creates an actual child VM instance with inherit: true for every repeated block. This is no longer the case with v-for: each repeated block in v-for is now a real partially compiled fragment, with a lightweight intermediate "scope". This greatly reduces the overhead and as a result you should see significant performance improvement for both initial rendering (up to 100% for non-component loops) and re-rendering with track-by (up to 50%, as tested in dbmonster).
  
  This also means:
  1. Using an extra <template> repeat no longer creates the overhead of a child instance.
  2. v-ref would not work on v-for if the repeated block is not a component, because there are no longer anonymous child instances created in that case.
3. Component Scoping
  
  Now this is the part that is the most different. Previously when you use a component with v-repeat, you get somewhat weird scoping:
```

<comp v-repeat="item in list"></comp>
```
  In the above example, item and $index are automatically available inside the component, but not in the parent template. If you do want to use $index in the parent template, you have to create a <template> to wrap the repeat. In addition, this requires the component implementation to be aware that it is v-repeat specific, because the external data is not received via the standard props interface.
  
  With v-for, you get the expected scoping:
```
<comp
  v-for="item in list"
  :id="$index"
  :data="item">
</comp>
```
  And you need to explicitly pass external data into the component as props. This makes your component implementation no longer v-repeat specific and less magical.
4. v-for also supports the v-for="(key, val) in obj" or v-for="(index, val) in arr" syntax. This allows nested loops to more easily reference the key or index.
5. v-for no longer uses track-by="$index" behavior for Arrays of primitive values by default. It now uses the value itself as the cache key. As a result, v-for will raise warning when the Array contains duplicate values and prompt the user to use track-by="$index" to handle duplicate values.
6. v-for no longer converts the value to Array before piping it through filters. Custom filters used on v-for will now get the raw value. However, the built-in filterBy and orderBy filters will convert the values into Arrays, so any filters after them will received the converted Array values.

v-class and v-style

v-class and v-style have been deprecated in favor of the new binding syntax (v-bind:class and v-bind:style). Bindings for class and style have some dedicated enhancements. You can pass in JavaScript Object or Array literals:

<!-- toggle classes -->
<div v-bind:class="{ 'class-a': true, 'class-b': false }"></div>
<!-- apply a list of classes -->
<div v-bind:class="[ dynamicClass, 'literal-class' ]"></div>

<!-- apply style object (camelCase accepted) -->
<div v-bind:style="{ fontSize: '14px', color: 'red' }"></div>
<!-- apply multiple style objects -->
<div v-bind:style="[ styleObjectA, styleObjectB ]"></div>

v-on

You can use the .stop and .prevent modifiers for calling stopPropagation() and preventDefault():

<!-- event won't propagate -->
<a v-on:click.stop="doThis"></a>

<!-- this will no longer reload the page! -->
<form v-on:submit.prevent></form>

The key filter for v-on has been deprecated. v-on can now leverage a Key Modifier that replaces the old key filter (you can use all the old aliases usable in the key filter, or use a direct keyCode):

<!-- before -->
<input v-on="
  keyup: handleEnter | key 'enter',
  keyup: handleEsc | key 'esc'">

<!-- after -->
<input
  @keyup.enter="handleEnter"
  @keyup.esc="handleEsc">

v-on will now also listen to custom Vue events (emitted via vm.$emit) when it is used on a child component. The idea is that props and events should constitute the public API of a component:
- props for passing data down;
- events for handling actions up.
A typical component would look like this:
```
<item-list
  v-bind:items="items"
  v-bind:mode="active"
  v-on:ready="onItemsReady"
  v-on:update="onItemsUpdate">
</item-list>
```
With shorthand:
```
<item-list
  :items="items"
  :mode="active"
  @ready="onItemsReady"
  @update="onItemsUpdate">
</item-list>
```

v-ref and v-el

v-el and v-ref were previously "literal" directives, but you just need to give them an argument. Also, to make things more explicit, vm.$ is now vm.$refs, and vm.$$ is now vm.$els.
```

<comp v-ref:child></comp>

{{$refs.child.msg}}


<div v-el:node></div>
```
Caveat: camelCase names are converted to all lowercase when the HTML is parsed:
```
<comp v-ref:someThing></comp>
```
Gets rendered as:
```
<comp v-ref:something></comp>
```
Thus, it is necessary to use the dash-case <-> camelCase mapping for refs too (similar to props):
```
<comp v-ref:some-thing></comp>
{{ $refs.someThing.msg }}
```
v-model
- multiple checkbox input can now be bound to the same v-model value (must be an Array):
```
<input type="checkbox" value="Jack" v-model="checkedNames">
<input type="checkbox" value="John" v-model="checkedNames">
<input type="checkbox" value="Mike" v-model="checkedNames">
```
  With checkedNames' initial value being an Array, the checked boxes' values will be pushed into the Array, while unchecked ones will be removed from it. For example, if we check the first two boxes, checkedNames will have the value ["Jack", "John"]. Of course, you can also dynamically bind the value with v-bind.
- The options param for <select v-model> has been deprecated. You can now just use v-for to render the options and it will work properly with the v-model on the containing <select> element.
v-component
- v-component has been deprecated in favor of the is attribute. Details
- The wait-for param for components has been deprecated in favor of the new activate lifecycle hook. Details
New Directive
- Added v-else directive. Docs

Component API Changes

<content> outlet has been deprecated in favor of the new <slot> API. Details
Props syntax has changed as part of the new binding syntax.
$data can no longer be used as a prop.
Props with the data- prefix are now longer supported.
Literal props will no longer be auto-casted into Booleans or Numbers - they are now always passed down as Strings.

Filter Changes

The orderBy filter now expects its second argument to be a number instead of a boolean. The argument was originally called reverse, and is now called order. A value that is greater than or equal to 0 indicates ascending order, a value smaller than 0 indicates descending order. As a result, the old syntax for descending order still works:
```
<li v-for="user in users | orderBy 'name' -1">
  {{ user.name }}
<li>
```

General API Changes

The prefix global config has been deprecated. All directives will now consistently use the v- prefix.
The strict global config has been deprecated. Asset resolution is now always in strict mode. Details
The interpolate global config has been deprecated. Use v-pre on elements that should be skipped by the template compiler.
The proto global config has been deprecated. This has served no practical purpose and almost never used.
The inherit option has been deprecated. Alway pass data to child components via props.
The $add method has been deprecated for both Vue instances and observed objects. Use $set instead. Details
Event propagation for events sent via $dispatch and $broadcast now stops when it triggers a handler for the first time, unless the handler explicitly returns true. Details
$dispatch now also triggers the event on the instance calling it.
Vue no longer extends Object.prototype with $set and $delete methods. This has been causing issues with libraries that rely on these properties in certain condition checks (e.g. minimongo in Meteor). Instead of object.$set(key, value) and object.$delete(key), use the new global methods Vue.set(object, key, value) and Vue.delete(object, key).
Array.prototype.$remove: now always treats the argument as the item to search for. (Previously it treats the argument as an index if the argument is a number).
Instance method vm.$addChild() has been deprecated. Instead, a new option, parent has been (re)introduced. The usage is pretty simple:
```
// before
var child = parent.$addChild(options)

// after
var child = new Vue({ parent: parent })
```
Global asset registration methods, e.g. Vue.component, now returns the registered asset. This means you can now create, globally register and get reference to a component constructor in one step:
```
var MyComponent = Vue.component('my-component', options)

// equivalent to:
var MyComponent = Vue.extend(options)
Vue.component('my-component', MyComponent)
```
vm.$log() messages now also include computed properties.
Prop expressions now support filters.

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1.0.0 Evangelion

About the Release

Known Issues

Upgrade Guide

General Tips

Notable Changes

Template Syntax Change

Strict Mode by Default

Bye v-repeat, Hi v-for

<slot> is the new <content>

Full Changelog (from 0.12.16)

Template Syntax Changes

Directive Arguments

Literal Directives

Attribute Bindings

Props

Shorthands

Directive Changes

v-for

v-class and v-style

v-on

v-ref and v-el

v-model

v-component

New Directive

Component API Changes

Filter Changes

General API Changes