How to convert a string to number in TypeScript?

Given a string representation of a number, how can I convert it to number type in TypeScript?

var numberString: string = "1234";
var numberValue: number = /* what should I do with `numberString`? */;

Exactly like in JavaScript, you can use the parseInt or parseFloat functions, or simply use the unary + operator:

var x = "32";
var y: number = +x;

All of the mentioned techniques will have correct typing and will correctly parse simple decimal integer strings like "123", but will behave differently for various other, possibly expected, cases (like "123.45") and corner cases (like null).

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Stack Overflow Q#14667713, score: 2500