angular-cn/packages/core/schematics/migrations/template-var-assignment
Alan Agius 80394ce08b fix(core): TypeScript related migrations should cater for BOM (#30719)
fix(@schematics/angular): TypeScript related migrations should cater for BOM

In the CLI `UpdateRecorder` methods such as `insertLeft`, `remove` etc.. accepts positions which are not offset by a BOM. This is because when a file has a BOM a different recorder will be used https://github.com/angular/angular-cli/blob/master/packages/angular_devkit/schematics/src/tree/recorder.ts#L72 which caters for an addition offset/delta.

The main reason for this is that when a developer is writing a schematic they shouldn't need to compute the offset based if a file has a BOM or not and is handled out of the box.

Example
```ts
recorder.insertLeft(5, 'true');
```

However this is unfortunate in the case if a ts SourceFile is used and one uses `getWidth` and `getStart` method they will already be offset by 1, which at the end it results in a double offset and hence the problem.

Fixes #30713

PR Close #30719
2019-05-30 20:48:45 -07:00
..
angular refactor(core): template-var-assignment migration incorrectly warns (#30026) 2019-04-22 11:16:19 -07:00
google3 build: update rules_nodejs and clean up bazel warnings (#30370) 2019-05-14 10:08:45 -07:00
BUILD.bazel build: update rules_nodejs and clean up bazel warnings (#30370) 2019-05-14 10:08:45 -07:00
README.md refactor(core): polish failure messages for template-var-assignment schematic (#29708) 2019-04-08 09:46:57 -07:00
analyze_template.ts refactor(core): template-var-assignment migration incorrectly warns (#30026) 2019-04-22 11:16:19 -07:00
index.ts fix(core): TypeScript related migrations should cater for BOM (#30719) 2019-05-30 20:48:45 -07:00

README.md

Assignments to template variables

With Ivy, assignments to template variables are no longer supported as template variables are effectively constants.

This means that assignments to template variables will break your application once Ivy is enabled by default. For example:

<button *ngFor="let option of options"
       (click)="option = 'newButtonText'">
  {{ option }}
</button>

In the example from above, a value is assigned to the option template variable on click. This will ultimately break your application and therefore the logic needs to be adjusted to not update the option variable, but rather the given element in the options array:

<button *ngFor="let option of options; let idx = index"
       (click)="options[idx] = 'newButtonText'">
  {{ option }}
</button>