Angular Typescript无法从键值对获取键值

Question

I added an array of keyvalue for months.

  months : { [key: number]: string } = { 1: 'January', 2: 'February', 3: 'March', 
  4: 'April', 5: 'May', 6: 'June', 7: 'July', 8: 'August', 9: 'September', 10: 'October',
  11: 'November', 12: 'December' } 

I can get the value without any issues

var firstMonth= this.months[0].valueOf();

However, I can't get the key value.

I tried this.months[0].key. this does not work

When I used var firstMonth = this.months[0] , I only see the value of 'January'. I don't see the keyvalue when accessing one of the element in the array. When I hover over the array, I see all the months with both key values.

I see the example of using *ngFor in stackblitz for angular6-keyvaluepipe-demo but I can't access the key value in the typescript file.

Any help is appreciated.

Answer 1

Take a look at using Object.keys(this.months) .

While this may look very similar to key/value pairs, it's actually a form of indexing.

If you want to have key/value behavior out of the box, you should look at using a Map<number, string> .