js octal number All In One

js octal number All In One

const user = {
  name: "Hayes",
  id: 0,
};

interface User {
  name: string;
  id: number;
};


const user1: User = {
  name: "Eric",
  id: 0o7,
  // id: 007,
};

/*

Octal literals are not allowed in strict mode.ts(1121)
Octal literals are not available when targeting ECMAScript 5 and higher. Use the syntax '0o7'.ts(1085)

*/


const user2: User = {
  name: "Eric",
  id: '007',
};

/*

Type 'string' is not assignable to type 'number'.ts(2322)
defined-types.ts(9, 3): The expected type comes from property 'id' which is declared here on type 'User'

*/

Octal number (0o)

// ES-old

var n = 0755; 
// 493
var m = 0644; 
// 420

// ES2015 / ES6

var a = 0o10; 
// 8

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Numbers_and_dates#octal_numbers

Hexadecimal number (0X / 0x)

0xFFFFFFFFFFFFFFFFF // 295147905179352830000
0x123456789ABCDEF   // 81985529216486900
0XA                 // 10

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Numbers_and_dates#hexadecimal_numbers

refs

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Numbers_and_dates

https://stackoverflow.com/questions/37003770/why-javascript-treats-a-number-as-octal-if-it-has-a-leading-zero

http://www.javascripter.net/faq/octalsan.htm

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