Ytukyg

I have constants declared in the constructor in my .ts file. I'd like to display their value in the template.

Is it good practices?

EDIT:

import {Component, OnInit, Output} from '@angular/core';

import { NavController } from 'ionic-angular';

import {MemoryEditPage} from "../memory-edit/memory-edit";





@Component({

    selector: 'page-memory-list',

    templateUrl: 'memory-list.html',

})

export class MemoryListPage implements OnInit {



    @Output() k_user: string;

    @Output() type: MemoryType = MemoryType.memories;





    constructor(

        private auth: AuthService,

        public navCtrl: NavController,

    ) {

        const monthNames = ['Janvier','Février','Mars','Avil','Mai','Juin','Juillet','Août','Septembre','Octobre','Novembre','Décembre'];

        const thisMonth = monthNames[(new Date()).getMonth()];

        const dayNames = ['Lun','Mar','Mer','Jeu','Ven','Sam','Dim'];

        const thisDay = dayNames[(new Date()).getDay() - 1];

        const thisDate = (new Date()).getDate();



        this.thisDay = thisDay;

        this.thisDate = thisDate;

        this.thisMonth = thisMonth;



    }





}

Template:

<ion-label no-margin text-uppercase color="white">{{thisMonth}}</ion-label>

It can't be considered as a practice in the first place as you can't do it. You can only access a Component's (public) Properties and methods in your Component's Template.

You'll have to define a property on your Component for that.

...

@Component({...})

export class MemoryListPage implements OnInit {



    ...

    thisMonth;



    constructor(...) {

        ...

        const thisMonth = monthNames[(new Date()).getMonth()];

        this.thisMonth = thisMonth;

        ...

    }

}

And then use it in your template:

<ion-label 

  no-margin 

  text-uppercase 

  color="white">

  {{thisMonth}}

</ion-label>

UPDATE:

Answering your updated question, it's not really a good practice to write any instantiation logic in the constructor. It should be written in ngOnInit. Even the Angular's Official Docs vouch for this:

Experienced developers agree that components should be cheap and safe to construct.

Misko Hevery, Angular team lead, explains why you should avoid complex constructor logic.