Vue 2.4.0 正式发布，服务器端渲染+异步组件

[bluezhan]

Vue 2.4.0 正式发布了，Vue 是一款轻量级 JavaScript MVVM框架。

"Fear is freedom! Subjugation is liberation! Contradiction is truth!"
"恐惧就是自由！征服就是解放！矛盾就是真理！"

新版了带来一些改进和 bug 修复，具体如下：

更新：

• Full SSR + async component support in core: SSR now supports rendering async components used anywhere and the client also supports async components during the hydration phase. This means async components / code-splitting now just works during SSR and is no longer limited at the route level. (9cf6646 & 7404091)

• Easier creation of wrapper components: (6118759)

  • New component option: inheritAttrs. Turns off the default behavior where
    parent scope non-prop bindings are automatically inherited on component root
    as attributes.
  • New instance properties: $attrs & $listeners. $attrs contains the parent-scope attribute bindings that were not recognized as props, and $listeners contains the v-on listeners registered in the parent scope (without the .native modifier). These are essentially aliases of $vnode.data.attrs and $vnode.data.on, but are reactive.
  • Combining these allows us to simplify a component like this down into this:

    <div>
     <input v-bind="$attrs" v-on="$listeners">
    </div> 
    

  • Based on discussion in #5983.

• v-on: support v-on object syntax with no arguments. This pairs well with the new $listeners instance property when creating higher-order components. Note this syntax does not support modifiers. (11614d6)

• Now auto-resolves ES module default export when resolving async components. This enables keeping using the simpler const Foo = () => import('./Foo.vue') syntax when declaring async components with the changes introduced in vue-loader@13.0.0. (0cd6ef3)

• support .sync modifier for v-bind="object" (#5943) (3965e50), closes #5937

• keep-alive: support Array for include and exclude (#5956) (51c595a)

• weex: implement "weex.supports" api to support feature detection (#6053) (b1512d8)

• vm.$watch now also supports using the same object format supported by the watch component option: { handler: () => {}, deep: true } (#5645) (5aac170)

• types: add types for vue-server-renderer (#5775) (e6de9a5)

• Vue.config.errorHandler now also captures errors thrown in custom event handlers (#5709) (11b7d5d)

• add new config option Vue.config.warnHandler for defining a custom callback for runtime warnings. This only works in the development build. (#5883) (9881b40)

• add comments option to allow preserving comments in template (#5951) (e4da249), closes #5392

性能改进：

• ssr: vue-template-compiler now has two new SSR-specific compile methods that generates SSR-specific render function code by optimizing parts of the template into string concatenation. This improves raw SSR render performance by 2~8x depending on how much of the template can be optimized. Note this will have a much smaller impact on requests per second for a real app because raw render performance is only a small portion of the overall time spent in a request.
• This is enabled by default in vue-loader@>=12 and can be disabled using the optimizeSSR option.
• remove src directory from npm module, which should reduce download size when installing from npm. (#6072) (e761573)

官方为 Vue 创建了一个全新的服务器端渲染指南，建议所有使用者阅读。此外，还更新了 HackerNews 的 Demo，以反映最新的最佳做法。

Bug 修复：

• check enterToClass/leaveToClass existence before adding it (#5912) (34d8c79)
• ensure cleanup in watcher.get (#5988) (f6cd44c), closes #5975
• improve Vue.set/Vue.delete API to support multi type of array index (#5973) (eea0920)
• multiple merged vnode hooks not invoked properly (91deb4f), closes #6076
• prefetch should not have as attribute (#5683) (ebca266)
• core: add merge strategy for provide option (#6025) (306997e), closes #6008
• support plugin with multi version vue (#5985) (049f317), closes #5970
• core: should preserve reactivity-ness of injected objects (8d66691), closes #5913
• parser: the first newline following pre and textarea tag should be ignored (#6022) (4d68079)
• ref: refactor function registerRef (#6039) (254d85c), closes #5997
• ssr: fix bundleRenderer mapped async chunks caching check (#5963) (de42186)
• ssr: reference error when create $ssrContext for root component (#5981) (5581654), closes #5941
• transition group should work with dynamic name (#6006) (#6019) (d8d4ca6)
• v-model: fix input change check for type="number" (0a9aab5), closes #6069
• v-model: use consistent behavior during IME composition for other text-like input types (fix #5902) (4acc8c8)
• v-bind object should not override props on scopedSlots (#5995) (458030a)
• fix out-in transition for async components (#5760) (c3cdfcf)
• fix memory leak by preventing data.pendingInsert from keeping reference to removed nodes (#5839) (4733408)
• reduce memory usage by avoiding keeping reference to old vdom tree after patch (#5851) (07a3726)
• fix XHTML compatibility (#5852) (69f946b)
• Merge inject option when extending a component (#5827) (080c387)
• support string index when using Vue.set on Array (#5889) (8a2c514)
• ignore reserved attributes (is, ref, ...) in v-bind object syntax (#5881) (d33c125)
• fix slot resolved incorrect with abstract component (#5888) (213f136)

更新内容较多，详情请参阅发布说明：https://github.com/vuejs/vue/releases/tag/v2.4.0