Using ngClass for conditional styling, here is the usage from the docs:
/** * @ngModule CommonModule * * @usageNotes * ``` * <some-element [ngClass]="'first second'">...</some-element> * * <some-element [ngClass]="['first', 'second']">...</some-element> * * <some-element [ngClass]="{'first': true, 'second': true, 'third': false}">...</some-element> * * <some-element [ngClass]="stringExp|arrayExp|objExp">...</some-element> * * <some-element [ngClass]="{'class1 class2 class3' : true}">...</some-element> * ``` * * @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. * * @publicApi */
It is also recommended when the conditional logics is complicated, we can using Function:
<div [ngClass]="getCondClass(i)" *ngFor="let item of items as collection; index as i; first as isFirst; last as isLast; even as isEven; odd as isOdd;"> {{i + 1}}: {{item}} -- {{collection}} </div>
getCondClass (index) { if (index + 1 === 3) { // Using array to add 'third', 'very*important' classes return ['third', 'very-important']; } if (index === this.items.length - 1) { // Using string to add class return 'last'; } if (index === 0) { // Using object to add class return {'first': true}; } }