Javasript data types and how to determine data types

In JavaScript there is a common
5 basic data types, respectively: number,string,boolean,null,undefined
7 Types of references are: Object type, array type, date type, regexp type, function type, basic wrapper type, monomer built-in object.
* Note the value (object) of the reference type is an instance of the reference type. In ECMAScript, it is used to combine data and functionality. It has long been a class, but it is not appropriate to call it "[1]
How do we judge the data type, and when we want to determine what data type a variable belongs to, JavaScript provides the way that we can judge it?

With the basic data type number and reference type array class example//Method 1:typeof

var b = 222; var c= [];alert (typeof B); // number alert (typeof C); // Object

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Method 2 Instanceof The method is limited to reference type usage. and pay attention to capitalization.

1 var b = 222; 2 var c= [n/a]; 3 instanceof number); // Error 4 instanceof Array); // true 5 instanceof Array); // true

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Method 3 Constructor

1 var b = 222; 2 var c= [n/a]; 3 alert (c.constructor = = = Array); // true 4 alert (B.constructor = = number); // True This should be JavaScript automatically converting variables to basic wrapper types

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Method 4 prototype pay attention to case

 1  var  b = 222  2  var  c= [All ];  3  alert (Object.prototype.toString.call (b) = = = ' [Object number] '); // false  4  alert ( Object.prototype.toString.call (c) = = = ' [Object Array] '); // false  5  alert (Object.prototype.toString.call (b) = = = ' [Object Array] ') // true  6  alert ( Object.prototype.toString.call (c) = = = ' [object Array] ') // true  

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Reference:
[1] [High-performance JavaScript programming]. (High.Performance.JavaScript). Nicholas.c.zakas. Chinese-English version

Javasript data types and how to determine data types