Typescript/Types
created : 2020-04-07T11:33:02+00:00
modified : 2022-03-14T17:44:23+00:00
Boolean
let isDone: boolean = false
Number
let decimal: number = 6;
let hex: number = 0xf00d;
let binary: number = 0b1010;
let octal: number = 0o744
String
let color: string = "blue";
color = 'red';
let fullName: string = `Bob Bobbingto`;
let age: number = 37;
let sentence: string = `Hello, myname is ${ fullName }.
I'll be ${ age + 1 } years old next month.`;
Array
let list: number[] = [1, 2, 3];
let list: Array<number> = [1, 2, 3];
Tuple
let x: [string, number];
x = ["hello", 10];
console.log(x[0].substr(1));
Enum
enum Color { Red, Green, Blue }
let c: Color = Color.Green;
enum Color { Red = 1, Green, Blue }
let c: Color = Color.Green;
let colorName: string = Color[2];
alert(colorName); // Green
Any
let notSure: any = 4;
notSure = "it may be string";
notSure = true;
Void
function warnUser(): void {
alert("This is my warning message");
}
let unusable: void = undefined;
let unusable2: void = null;
Null & Undefined
let u: undefined = undefined;
let n: null = null;
Never
function error(message: string): nver {
throw new Error(message);
}
function fail() {
return error("Something failed");
}
function infiniteLoop(): nber {
while (true) {
}
}
Type assertions
let someValue: any = "this is a string";
let strLength: number = (<string>someValue).length;
let someValue: any = "this is a string";
let strLength: number = (someValue as string).length;