NgClass

Adds and removes CSS classes on an HTML element.

API

class NgClass implements DoCheck {
  constructor(_ngEl: ElementRef<any>, _renderer: Renderer2): NgClass;
  @Input('class') set klass(value: string);
  @Input() set ngClass(value: string | string[] | Set<string> | { [klass: string]: any; } | null | undefined);
}

constructor

NgClass

@param_ngElElementRef<any>

@param_rendererRenderer2

@returnsNgClass

klass

string

string | string[] | Set<string> | { [klass: string]: any; } | null | undefined

ngDoCheck

void

@returnsvoid

Description

Adds and removes CSS classes on an HTML element.

The CSS classes are updated as follows, depending on the type of the expression evaluation:

string - the CSS classes listed in the string (space delimited) are added,
Array - the CSS classes declared as Array elements are added,
Object - keys are CSS classes that get added when the expression given in the value evaluates to a truthy value, otherwise they are removed.

Exported by

CommonModule

Usage Notes

<some-element [ngClass]="stringExp|arrayExp|objExp|Set">...</some-element>

<some-element [ngClass]="{'class1 class2 class3' : true}">...</some-element>

For more simple use cases you can use the class bindings directly. It doesn't require importing a directive.

<some-element [class]="'first second'">...</some-element>

<some-element [class.expanded]="isExpanded">...</some-element>

<some-element [class]="['first', 'second']">...</some-element>

<some-element [class]="{'first': true, 'second': true, 'third': false}">...</some-element>