When passing an object to the Vue instance as it’s data property, Vue.js walks through all it’s properties and converts them to getter/setters  using Object.defineProperty.

For every directive / data binding in the template, there will be a corresponding watcher object. When a dependency’s setter is called, it triggers the watcher to re-evaluate, and in turn causes its associated directive to perform DOM updates.

<!-- Vue syntax above
     Angular 1.x syntax below -->

<h1 v-if="ok">{{ name }}</h1>
<h1 v-else>No</h1>
<h1 ng-if="ok">{{ name }}</h1>
<h1 ng-if="!ok">No</h1>

<input type="text" v-model="name">
<input type="text" ng-model="name">

<small v-show="!ok">{{ Not OK! | capitalize }}</small>
<small ng-show="!ok">{{ Not OK! | capitalize }}</small>

<a v-bind:href="url">Go back</a>
<a ng-href="{{ url }}">Go back</a>

<button v-on:click="doSomething">Do something</button>
<button ng-click="doSomething">Do something</button>

<!-- Vue syntax above
     Angular 1.x syntax below -->

<div v-bind:class="{ 'class-a': isA, 'class-b': isB }"></div>
<div ng-class="{ 'class-a': isA, 'class-b': isB }"></div>

<ul id="example-1">
  <li v-for="item in items">
    {{ item.message }}
  </li>
</ul>
<ul id="example-1">
  <li ng-repeat="item in items">
    {{ item.message }}
  </li>
</ul>

<!-- full syntax -->
<button v-bind:disabled="someDynamicCondition">Button</button>

<!-- shorthand -->
<button :disabled="someDynamicCondition">Button</button>

or

<!-- full syntax -->
<a v-on:click="doSomething"></a>

<!-- shorthand -->
<a @click="doSomething"></a>

// ...
computed: {
  fullName: {
    // getter
    get: function () {
      return this.firstName + ' ' + this.lastName
    },
    // setter
    set: function (newValue) {
      var names = newValue.split(' ')
      this.firstName = names[0]
      this.lastName = names[names.length - 1]
    }
  }
}
// ..

// When calling vm.fullName = 'John Doe', the setter will 
// be invoked and vm.firstName and vm.lastName 
// will be updated accordingly.

<div v-bind:style="{ color: activeColor, fontSize: fontSize + 'px' }"></div>

<!-- Works mostly the same as with classes -->

Additionally

When you use a CSS property that requires vendor prefixes in v-bind:style, for example transform, Vue.js will automatically detect and add appropriate prefixes to the applied styles.

<div v-if="show" transition="expand"></div>

/* always present */
.expand-transition {
  transition: all .3s ease;
  height: 30px;
  padding: 10px;
  background-color: #eee;
  overflow: hidden;
}

/* .expand-enter defines the starting state for entering */
/* .expand-leave defines the ending state for leaving */
.expand-enter, .expand-leave {
  height: 0;
  padding: 0 10px;
  opacity: 0;
}

var example1 = new Vue({
  el: '#example-1',
  data: {
    items: [
      { message: 'Foo' },
      { message: 'Bar' }
    ],
    object: {
      FirstName: 'John',
      LastName: 'Doe',
      Age: 30
    }
  }
})

<ul id="example-1">
  <li v-for="item in items">
    {{ $index }} – {{ item.message }}
  </li>
</ul

or 

<ul>
  <template v-for="item in items">
    <li>{{ item.msg }}</li>
    <li class="divider"></li>
  </template>
</ul>

<!-- Where the <template> element 
won’t render -->

or

<div v-for="(key, val) in object">
  {{ key }} {{ val }}
</div>

var vm = new Vue({
  el: '#example',
  data: {
    name: 'Vue.js'
  },
  // define methods under the `methods` object
  methods: {
    greet: function (user, event) {
      // `this` inside methods point to the Vue instance
      alert('Hello ' + user + ' this is ' + this.name + '!')
      // `event` gives us access to original DOM event 
    }
  }
})

// you can invoke methods in JavaScript too
vm.greet('Developers') // -> 'Hello Developers this is Vue.js!'

<button @click="greet('Developers', $event)">Greet</button>

<!-- the click event's propagation will be stopped -->
<a v-on:click.stop="doThis"></a>

<!-- the submit event will no longer reload the page -->
<form v-on:submit.prevent="onSubmit"></form>

<!-- modifiers can be chained -->
<a @click.stop.prevent="doThat">

<!-- just the modifier -->
<form v-on:submit.prevent></form>

<!-- only trigger handler if event.target is the element itself -->
<!-- i.e. not from a child element -->
<div @click.self="doThat">...</div>

<!-- Support for key aliases as modifiers -->
<input @keyup.enter="submit">

<!-- List of aliases: enter, tab, delete ,esc, space, up, down, left, right; 
or create your own with Vue.directive('on').keyCodes.f1 = 112 -->

var Child = Vue.extend({ /* ... */ })

var Parent = Vue.extend({
  template: '...',
  components: {
    // <my-component> will only be available in Parent's template
    'my-component': Child
  }
})

Vue.component('child', {
  // declare the props
  props: ['myProp'],
  // the prop can be used inside templates, and will also
  // be set as `this.msg`
  template: '<span>{{ myProp }}</span>'
})

<child my-prop="hello!"></child>
<!-- The prop will be passed as string -->

Remember: When using camelCased prop names as attributes, you need to use their kebab-case equivalents.

<div>
  <child :my-value="obj"></child>
</div>

var Parent = Vue.extend({
  template: '...',
  components: {
    Child
  },
  data: function () {
    return {
      obj: { name: 'Vue', ext: 'JS' }
    }
  }
})

This will pass the whole object as prop.

Vue.component('example', {
  props: {
    // basic type check (`null` means accept any type)
    propA: Number,
    // a required string
    propB: {
      type: String,
      required: true
    },
    // a number with default value
    propC: {
      type: Number,
      default: 100
    },
    // object/array defaults should be returned from a
    // factory function
    propD: {
      type: Object,
      default: function () {
        return { msg: 'hello' }
      }}}}

Vue.component('example', {
  props: {
    // indicate this prop expects a two-way binding. will
    // raise a warning if binding type does not match.
    propE: {
      twoWay: true
    },
    // custom validator function
    propF: {
      validator: function (value) {
        return value > 10
      }
    },
    // coerce function (new in 1.0.12)
    // cast the value before setting it on the component
    propG: {
      coerce: function (val) {
        return val + '' // cast the value to string
      }
    }
}

<!-- Component template -->
<div>
  <h1>This is my component!</h1>
  <slot>
    This will only be displayed if there is no content
    to be distributed.
  </slot>
</div>

<!-- Parent template -->
<my-component>
  <p>This is some original content</p>
  <p>This is some more original content</p>
</my-component>

<!-- Rendered result -->
<div>
  <h1>This is my component!</h1>
  <p>This is some original content</p>
  <p>This is some more original content</p>
</div>

(like transclusion in angularJS)

<!-- Component template -->
<div>
  <slot name="one"></slot>
  <slot></slot>
  <slot name="two"></slot>
</div>

<!-- Parent template -->
<multi-insertion>
  <p slot="one">One</p>
  <p slot="two">Two</p>
  <p>Default A</p>
</multi-insertion>

<!-- Rendered result -->
<div>
  <p slot="one">One</p>
  <p>Default A</p>
  <p slot="two">Two</p>
</div>

new Vue({
  el: 'body',
  data: {
    currentView: 'home'
  },
  components: {
    home: { /* ... */ },
    posts: { /* ... */ },
    archive: { /* ... */ }
  }
})

<component :is="currentView">
  <!-- component changes when vm.currentview changes! -->
</component>

<component :is="currentView" keep-alive>
  <!-- inactive components will be cached! -->
</component>

Vue.component('activate-example', {
  activate: function (done) {
    var self = this
    loadDataAsync(function (data) {
      self.someData = data
      done()
    })
  }
})

keep-alive

activate hook

Runs each time a component is dynamicaly swaped and at time of the inital render

transition-mode:

in-out

out-in

new in, then old out

old out, then new in

<!-- {{ msg }} will be compiled 
using the parent’s scope -->

<child-component>
  {{ msg }}
</child-component>

Everything in the parent template is compiled in parent scope; everything in the child template is compiled in child scope.

var mixin = {
  created: function () {
    console.log('mixin hook called')
  }
}

new Vue({
  mixins: [mixin],
  created: function () {
    console.log('component hook called')
  }
})

// -> "mixin hook called"
// -> "component hook called"

var mixin = {
  methods: {
    foo: function () {
      console.log('foo')
    },
    conflicting: function () {
      console.log('from mixin')
    }
  }
}

var vm = new Vue({
  mixins: [mixin],
  methods: {
    bar: function () {
      console.log('bar')
    },
    conflicting: function () {
      console.log('from self')
    }
  }
})

import Vuex from 'vuex'

const state = {
  counter: 0
}

const mutations = {
  INCREMENT (state) {
    state.counter++
  }
}

export default new Vuex.Store({
  state,
  mutations
})

store.dispatch('INCREMENT')

console.log(store.state.count) // -> 1

General

• NPM downloads: 382,184 ytd, ~52k/month current      

• GitHub Stars: 11,357 current

Repo Activity

• Releases: 54 ytd (from 0.11.5 to 1.0.12, including alpha/beta/rc releases)

• Commits: 1,023 ytd

• Issues Closed: 1,014 ytd

• Pull Requests Merged: 69 ytd from 43 contributors

Vuejs.org

• Page views: 3,761,728 ytd                                                   

• Unique visitors: 363,365 ytd     

• 30 Day Active Users: 76,090 current                                 

Yes, this is a personal project. So if you are looking for an enterprise backed dev team, Vue is probably not the one. But I’d rather look at the numbers. Vue has maintained 100% test coverage on every single commit since the 0.11 rewrite, and that will continue. GitHub issues are closed within an average of 13 hours, and there has been 1400+ of them. As of this writing, there are literally zero open and reproducible bugs.

— Evan You, Vue.js author

http://blog.evanyou.me/2015/12/20/vuejs-2015-in-review/