CODEWITHSUNDEEP
angular
user2004
user2004

Reputation: 1973

cannot set property number of undefined

I have a component and try to assign to an object some props. On try no1. I have no err but nothing is displayed on UI and in try no2 I have an error "cannot set property number of undefined".

days: Day[] = [];
now: Date = new Date();

ngOnInit() {
    this.days = [];

    for (let i = 0; i < this.numberOfDaysCurrentMonth; i++) {
        // try no.1
        this.days.forEach(x => x.number = i);
        this.days.forEach(x => x.weekDay = new Date(this.currentYear, this.currentMonth - 1, i).getDay());
        this.days.forEach(x => x.name = '')

        //try no.2
        this.days[i].number = i;
        this.days[i].weekDay = new Date(this.currentYear, this.currentMonth - 1, i).getDay());
        this.days[i].name = ''
    }

and 

export class Day {
    number: number;
    weekDay: number;
    name: string;
}

Upvotes: 1

Views: 250

Answers (2)

Oram
Oram

Reputation: 1673

What you need to do is add the day to the days array when you loop over this.numberOfDaysCurrentMonth

ngOnInit() {
  this.days = [];

  for (let i = 0; i < this.numberOfDaysCurrentMonth; i++) {
    let day = {
      number: i,
      weekDay: new Date(this.currentYear, this.currentMonth - 1, i).getDay(),
      name: ''
    }
    this.days.push(day);
  }
}

Your try with this.days.forEach doesn't do anything because it loops over each object in the days array which is empty.

Similarly, this.days[i] is really undefined because the array is empty.

Upvotes: 4

mika
mika

Reputation: 343

Your array is never filled with any entries. this.days.forEach is going to do something for every item in the array, but as the array is empty, i doesn't do anything.

You should populate the array first and then use forEach on it.

Upvotes: 0

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