After the introduction of the view engine, we can drop a lot of code that is not used any more.
This should reduce the size of the app bundles because a lot of this code was not being properly tree-shaken by today's tools even though it was dead code.
When the `enableLegacyTemplate` is set to `false`, `<template>` tags and the
`template` attribute are no more used to define angular templates but are
treated as regular tag and attribute.
The default value is `true`.
In order to define a template, you have to use the `<ng-template>` tag.
This option applies to your application and all the libraries it uses. That is
you should make sure none of them rely on the legacy way to defined templates
when this option is turned off (`false`).
The rationale of this change is to improve the inter-operability with web
components that might make use of the `<template>` tag.
DEPRECATION
The template tags and template attribute are deprecated:
<template ngFor [ngFor]=items let-item><li>...</li></template>
<li template="ngFor: let item of items">...</li>
should be rewritten as:
<ng-template ngFor [ngFor]=items let-item><li>...</li></ng-template>
Note that they still be supported in 4.x with a deprecartion warning in
development mode.
MIGRATION
- `template` tags (or elements with a `template` attribute) should be rewritten
as a `ng-template` tag,
- `ng-content` selectors should be updated to referto a `ng-template` where they
use to refer to a template: `<ng-content selector="template[attr]">` should be
rewritten as `<ng-content selector="ng-template[attr]">`
- if you consume a component relying on your templates being actual `template`
elements (that is they include a `<ng-content selector="template[attr]">`). You
should still migrate to `ng-template` and make use of `ngProjectAs` to override
the way `ng-content` sees the template:
`<ng-template projectAs="template[attr]">`
- while `template` elements are deprecated in 4.x they continue to work.
TypeScript compiler will now build to ES2015 code and modules. Babili is used to minify ES2015
code, providing an initial optimization that we couldn't previously get just from Uglify. Uses
Babel to convert ES2015 to UMD/ES5 code, and Uglify to minimize the output.
Some versions of TypeScript are super slow to compile functions that
contain a lot of `if` conditions in them. Splitting the handle event
expressions per element is similar to what we did in the old codegen.
Note that this does not yet include enabling the view engine
by default.
Included refactoring:
- view engine: split namespace of elements / attributes already
when creating the `NodeDef`
- view engine: when injecting the old `Renderer`, use an implementation
that is based on `RendererV2`
- view engine: store view queries in the component view, not
on the host element
Included refactoring:
- splits the `RendererV2` into a `RendererFactoryV2` and a `RendererV2`
- makes the `DebugRendererV2` a private class in `@angular/core`
- remove `setBindingDebugInfo` from `RendererV2`, but rename `RendererV2.setText` to
`RendererV2.setValue` and allow it on comments and text nodes.
Part of #14013
Aspects: di, query, content projection
Included refactoring:
- use a number as query id
- use a bloom filter for aggregating matched queries of nested elements
- separate static vs dynamic queries
Part of #14013
Included refactoring:
- make ViewData.parentIndex point to component provider index
- split NodeType.Provider into Provider / Directive / Pipe
- make purePipe take the real pipe as argument to detect changes
- order change detection:
1) directive props
2) renderer props
Part of #14013
PR Close#14412
Note that the duplication in tsconfig.json files will be fixed in a followup CL now that we have tsconfig inheritance
BREAKING CHANGE: Angular 4 will support only TypeScript 2.1, so we no longer provide backwards compatibility to TS 1.8.
Subclassing errors is problematic since Error returns a
new instance. All of the patching which we do than prevent
proper application of source maps.
PR Close#14160
