Angular2 Components - Dynamic Inline Styles

Question

I have a component that has a count and a color property. The component is supposed to display count number of <div>s with an inline style used to change its color to color.

Here's what I have so far:

@Component({
    selector: 'my-control',
    template: `<div *ngFor="let i of dummyArray" style="color: {{color}}"> COLOR = {{color}}</div>`
})
export class MyControl {
    private _count: number;
    @Input() set count(value: string) {
        this._count = +value;
    }
    @Input() set color(value: string) {
        this._color = value;
    }
    get dummyArray(): number[] {
        let ret: number = [];
        for (let i = 0; i < this._count; ++i) ret.push(i);
        return ret;
    }
    get color(): string {
        return this._color;
    }
}

This renders:

<my-control count="5" color="red">
    <div>COLOR = red</div>
    <div>COLOR = red</div>
    <div>COLOR = red</div>
    <div>COLOR = red</div>
    <div>COLOR = red</div>
</my-control>

Now I have two issues with this:

Is there any better way to render the <div>s count times without creating a dummy array?
More importantly, the inline styles are not being set. If I hardcode styles like style="color: red", it works. But style="color: {{color}}" does not. The element is rendered without any styles as you can see above.

For #2, I have also tried using the nativeElement's children as well:

@Input() set count(value: string) {
    this._count = +value;
    this.update();
}
@Input() set color(value: string) {
    this._color = value;
    this.update();
}
update(): void {
    for (let i = 0; i < this._count; ++i) {
        this.renderer.setElementStyle(this.elRef.nativeElement.children[i], 'color', this._color);
    }
}

But I get exception accessing the child elements as they don't exist apparently.

How should I go about solving these issues?

There is no way to us `ngFor` without an array. You could create your custom `ngFor` directive that does that. There is an issue to support `ngFor` with a number instead of an array but it's unlikely to be implemented. — Günter Zöchbauer, May 24 '16 at 15:53
thanks for the tip mate.. this sucks though.. makes for a clumsy implementation of components in such cases.. — AweSIM, May 24 '16 at 15:57
Your code can be optimized a bit. See http://stackoverflow.com/questions/36535629/repeat-html-element-multiple-times-using-ngfor-based-on-a-number — Günter Zöchbauer, May 24 '16 at 15:59
@GünterZöchbauer.. love it!.. this is a lot more elegant than what i have at present.. thanks for the tip.. =) — AweSIM, May 24 '16 at 16:05

score 20 · Accepted Answer · answered May 24 '16 at 15:52

20

<div *ngFor="let i of dummyArray" style="color: {{color}}>

is missing the closing " after color}}

Binding this way to style should be avoided because it doesn't work in all Safari versions (maybe also others).

Instead use

<div *ngFor="let i of dummyArray" [ngStyle]="{'color': color}">

answered May 24 '16 at 15:52

Günter Zöchbauer

623,577
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1

apologies.. i missed the ending `"` accidentally here.. the issue still remains.. let me check the `[ngStyle]="{'color': color}"` thingy and report back.. – AweSIM May 24 '16 at 15:55
2

this is the fastest ive ever gotten an answer.. im counting minutes to be able to mark this as the correct answer.. =) – AweSIM May 24 '16 at 16:03
now i have an additional question, if you can take out time for this one.. i lose all css animations if i use *ngFor.. is there a way around it? – AweSIM May 24 '16 at 16:34
Not sure what you mean by "loose". There are some known issues how `ngFor` treats changes in the array that don't work well with animation. See http://stackoverflow.com/questions/37217314/how-can-i-animate-ngfor-in-angular-2/37217476#37217476 – Günter Zöchbauer May 24 '16 at 16:42

score 3 · Answer 2 · answered May 24 '16 at 16:00

3

About your first question:

To create an array with ten undefined elements, you could do:

@Component({
  selector: 'my-app',
  template: `<div *ngFor="let i of arr(10); let index=index">hello {{index}}</div>`
})
export class AppComponent {
  arr=Array;
}

check this plunk

answered May 24 '16 at 16:00

Abdulrahman Alsoghayer

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7
51
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thanks for the tip mate.. unfortunately i can only accept one answer as the correct answer.. And Gunter's is more correct as it answers the more pressing issue.. =( – AweSIM May 24 '16 at 16:33
1

You are welcome @AweSIM. I totally agree Gunter's answer is the correct one. Also, the blasting speed of his answer has to be counted :) . It just that I had an addition to his answer and posted it. And now I see that he already commented on your question in relation to the issue I answered :D – Abdulrahman Alsoghayer May 24 '16 at 16:44

Angular2 Components - Dynamic Inline Styles

2 Answers2