How to convert a string to number in TypeScript?

Asked 9 years ago
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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`? */;

asked 9 years ago

Correct Answer

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).

Conversion table Table taken from this answer

answered 2 years ago

Other Answer

The Typescript way to do this would be:

Number('1234') // 1234
Number('9BX9') // NaN

as answered here:

answered 9 years ago