Another common primitive is the number. Since TypeScript is a superset of JavaScript, numbers work the same way in both languages. The openness of JavaScript allows for a broad set of numbers. Integers, signed floats, or unsigned floats are permitted. By default, a number will be base 10.
When a type is explicitly assigned to a variable, the type will be removed once the JavaScript is generated. The reason is that typing does not exist in JavaScript. It explains why TypeScript only has number. The following code will produce three variables without an explicit type in JavaScript but if typeof is used, it will return the dynamic type: number.
The number: integer, decimal, and signed
The number type is the same as in JavaScript: it defines the type for integer, float, double, etc. So integer, float, and positive or negative numbers will all be referred to as the single type, number. A type declared as number (implicitly or explicitly) can be checked at runtime as well with typeof which will return number.
Numbers are also not signed. This means they can be positive or negative.
let int: number = 1;
let float: number = 1.1;
let negative: number = -100;
console.log(typeof(int)); //number
console.log(typeof(float)); //number
console.log(typeof(negative)); //number
In TypeScript, as in JavaScript, the type number can be assigned with NaN meaning that it is not a number.
NaN
In TypeScript, as in JavaScript, the type number can be assigned with NaN meaning that it is not a number.
let myNumberIsNotANumber: number = NaN;
console.log(typeof(myNumberIsNotANumber)); // number