Enums

Helps to define a set of named constants.

Numeric Enum

The following members after Up are auto incremented.

enum Direction {
  Up = 1,
  Down,
  Left,
  Right
}

enum Direction {
  Up,
  Down,
  Left,
  Right
}

By default, Up will be initialized as 0 and rest other members are auto incremented.

String Enums

enum Direction {
  Up = "UP",
  Down = "DOWN",
  Left = "LEFT",
  Right = "RIGHT"
}

In string enums, each member has to be initialized.

enum types

Enums can be used as types also (but constants can't).

enum CHART_TYPES {
    LINE = 'line',
    LINE_FILL = 'line_fill',
    PIE = 'pie',
    BAR = 'bar',
    DOUGHNUT = 'doughnut'
}

let myChartType:CHART_TYPES;

enums can be used in custom types (but constants can't be)

type chartType = CHART_TYPES.LINE | 2 | 3 ;

Reference Links:

Enums EnumTutorial

Numeric Enum
String Enums
enum types