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3. Standard_Object.md

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Object Type

use typeof to get the type of a object

typeof 123; // 'number'
typeof NaN; // 'number'
typeof 'str'; // 'string'
typeof true; // 'boolean'
typeof undefined; // 'undefined'
typeof Math.abs; // 'function'
typeof null; // 'object'
typeof []; // 'object'
typeof {}; // 'object'

null is object, Array is object

Wrapper Object

Note:

  1. Do ## NOT ## use new Number()、new Boolean()、new String() to create wrapper object
  2. Use String to convert any type to string, or use toString() for a object
  3. Do not need to convert any type to boolean
  4. typeof could get number、boolean、string、function and undefined
  5. Use Array.isArray(arr)
  6. Use myVar === null

Date

Create a date object:

var d = new Date(2015, 5, 19, 20, 15, 30, 123);
d; // Fri Jun 19 2015 20:15:30 GMT-0700 (Pacific Daylight Time)

RegExp

https://www.regextester.com/

var re1 = /ABC\-001/
var re2 = new RegExp('ABC\\-001');

re.test('mock string'); // return true or false
  1. Group: exec()
  2. Greedy match: ?
  3. Global search: g

JSON (JavaScript Object Notation)

Data type:

  • number
  • boolean
  • string
  • null
  • array -- []
  • object -- { ... }

Must use " "

JSON.stringfy(object) convert object to string with JSON format JSON.parse(JSON) convert JSON format string to object