Adding a stylesheet dynamically in Angular 2: A step-by-step guide

Question

Adding a stylesheet dynamically in Angular 2: A step-by-step guide

Is there a method to dynamically add a stylesheet URL or <style></style> in Angular2?

For instance, if the variable isModalOpened is set to true, I want to apply certain CSS styles to elements outside of my root component, such as the body or html.

Although this can be achieved with DOM manipulation or jQuery, I am seeking a solution using Angular 2.

Is it possible?

Thank you.

javascript html css angular angular2-template

Answer 1

Answer №1

If you want to dynamically create a <style> tag, you can do so using the following method:

ngOnInit() {
  const css = 'a {color: pink;}';
  const head = document.getElementsByTagName('head')[0];
  const style = document.createElement('style');
  style.type = 'text/css';
  style.appendChild(document.createTextNode(css));
  head.appendChild(style);
}

Answer 2

If you want to dynamically create a <style> tag, you can do so using the following method:

ngOnInit() {
  const css = 'a {color: pink;}';
  const head = document.getElementsByTagName('head')[0];
  const style = document.createElement('style');
  style.type = 'text/css';
  style.appendChild(document.createTextNode(css));
  head.appendChild(style);
}

Answer 3

Answer №2

It is uncertain if the changes can be applied to the body or html elements directly, but they can definitely be made to the root component.

To achieve this, create a service that is injected into the root component.
This service should have a state, possibly using a BehaviorSubject.
Access the service and update the state whenever the value of isModalOpened changes.
In the root component, monitor this change and modify the parameter values of the components accordingly.
Within the root component's HTML, adjust the class values based on the component's parameter values.

Update: Changing background color from within an inner component.

app.component.css

.red{
    background: red;
 }

.white{
    background: white;
 }
.green{
    background: green;
 }

app.component.html

<div  [ngClass]="backgroundColor" ></div>

app.component.ts

constructor(private statusService: StatusService) {
    this.subscription = this.statusService.getColor()
    .subscribe(color => { this.backgroundColor = color; });
}

status.service.ts

private color = new Subject<any>();
public setColor(newColor){
    this.color.next(newColor);
}
public getColor(){
    return this.color.asObservable();
}

child.component.ts

export class ChildComponent {
    constructor(private statusService: StatusService) {}

    setColor(color:string){
      this.statusService.setColor(color);
    }
}

By calling setColor with 'red', 'green', or 'white' as the color variable, the background color of the root component will change accordingly.

Answer 4

It is uncertain if the changes can be applied to the body or html elements directly, but they can definitely be made to the root component.

To achieve this, create a service that is injected into the root component.
This service should have a state, possibly using a BehaviorSubject.
Access the service and update the state whenever the value of isModalOpened changes.
In the root component, monitor this change and modify the parameter values of the components accordingly.
Within the root component's HTML, adjust the class values based on the component's parameter values.

Update: Changing background color from within an inner component.

app.component.css

.red{
    background: red;
 }

.white{
    background: white;
 }
.green{
    background: green;
 }

app.component.html

<div  [ngClass]="backgroundColor" ></div>

app.component.ts

constructor(private statusService: StatusService) {
    this.subscription = this.statusService.getColor()
    .subscribe(color => { this.backgroundColor = color; });
}

status.service.ts

private color = new Subject<any>();
public setColor(newColor){
    this.color.next(newColor);
}
public getColor(){
    return this.color.asObservable();
}

child.component.ts

export class ChildComponent {
    constructor(private statusService: StatusService) {}

    setColor(color:string){
      this.statusService.setColor(color);
    }
}

By calling setColor with 'red', 'green', or 'white' as the color variable, the background color of the root component will change accordingly.

Answer 5

Answer №3

Create a custom directive and encapsulate all your HTML code within it - let's name it ngstyle...

To include your ngstyle on the page, simply use the directive tags like so:

<ngstyle><ngstyle>

You can also incorporate logic into your directive using ng-if to allow for toggling:

<ngstyle ng-if="!isModalVisible"><ngstyle>

If you have 'isModalVisible' defined in your controller scope as follows:

$scope.isModalVisible = false; //or true, depending on your requirements

...you can easily switch its value between true and false through various methods, thereby toggling the visibility of your directive.

Answer 6

Create a custom directive and encapsulate all your HTML code within it - let's name it ngstyle...

To include your ngstyle on the page, simply use the directive tags like so:

<ngstyle><ngstyle>

You can also incorporate logic into your directive using ng-if to allow for toggling:

<ngstyle ng-if="!isModalVisible"><ngstyle>

If you have 'isModalVisible' defined in your controller scope as follows:

$scope.isModalVisible = false; //or true, depending on your requirements

...you can easily switch its value between true and false through various methods, thereby toggling the visibility of your directive.

Adding a stylesheet dynamically in Angular 2: A step-by-step guide

Answer №1

Answer №2

Answer №3

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