ngStyle VS Renderer2 ? What should I use?

Question

I\'m using Angular 5.2.9.

I was wondering when should I use Renderer2 over ngStyle ? Which is the best solution ?

1:

FOO BAR

Answer 1

Both ngStyle and renderer.setStyle are used to dynamically style a component

But renderer.setStyle looks to take precedence over [ngStyle] even if ngStyle looks to be a type of embedded style.

Demo example:

https://stackblitz.com/edit/angular-jtdk4z?file=src%2Fapp%2Fapp.component.html

When looking to the internal implementation of ngStyle:

https://github.com/angular/angular/blob/master/packages/common/src/directives/ng_style.ts

it looks like it itself is implemented using renderer.setStyle

@Directive({selector: '[ngStyle]'})
export class NgStyle implements DoCheck {
  private _ngStyle: {[key: string]: string};
  private _differ: KeyValueDiffer;

  constructor(
      private _differs: KeyValueDiffers, private _ngEl: ElementRef, private _renderer: Renderer2) {}

  @Input()
  set ngStyle(v: {[key: string]: string}) {
    this._ngStyle = v;
    if (!this._differ && v) {
      this._differ = this._differs.find(v).create();
    }
  }

  ngDoCheck() {
    if (this._differ) {
      const changes = this._differ.diff(this._ngStyle);
      if (changes) {
        this._applyChanges(changes);
      }
    }
  }

  private _applyChanges(changes: KeyValueChanges): void {
    changes.forEachRemovedItem((record) => this._setStyle(record.key, null));
    changes.forEachAddedItem((record) => this._setStyle(record.key, record.currentValue));
    changes.forEachChangedItem((record) => this._setStyle(record.key, record.currentValue));
  }

  private _setStyle(nameAndUnit: string, value: string|number|null|undefined): void {
    const [name, unit] = nameAndUnit.split('.');
    value = value != null && unit ? `${value}${unit}` : value;

    if (value != null) {
      this._renderer.setStyle(this._ngEl.nativeElement, name, value as string);
    } else {
      this._renderer.removeStyle(this._ngEl.nativeElement, name);
    }
}