A simple method (recommended) for js to judge various data types. js Data Types

A simple method (recommended) for js to judge various data types. js Data Types

Anyone who knows about js knows that there is a typeof used to judge various data types. There are two ways to write: typeof xxx, typeof (xxx)

Example:

Typeof 2 output number

Typeof null Output object

Typeof {} output object

Typeof [] Output object

Typeof (function () {}) Output function

Typeof undefined output undefined

Typeof '200' output string

Typeof true outputs boolean

Five data types in js are included in this section: number string boolean undefinedobject and function type function.

Here you will certainly ask: how can I differentiate objects, arrays, and null?

Next we will use another tool: Object. prototype. toString. call

This is a native prototype Extension function of the object, which is used to distinguish data types more accurately.

Let's try this fun:

Var gettype = Object. prototype. toString

Gettype. call ('aaa') Outputs [object String]

Gettype. call (2222) Output [object Number]

Gettype. call (true) Output [object Boolean]

Gettype. call (undefined) Output [object Undefined]

Gettype. call (null) Output [object Null]

Gettype. call ({}) Output [object Object]

Gettype. call ([]) Output [object Array]

Gettype. call (function () {}) output [object Function]

We have solved the problem.

In fact, there are many types of judgment in js

[Object HTMLDivElement] div object,
[Object HTMLBodyElement] body object,
[Object Document] (IE) or
[Object HTMLDocument] (firefox, google )......

Various dom node judgments are used when we write plug-ins.

The encapsulation method is as follows:

var  gettype=Object.prototype.toStringvar  utility={isObj:function(o){    return  gettype.call(o)=="[object Object]"; },     isArray:function(o){        return  gettype.call(o)=="[object Array]";     },     isNULL:function(o){        return  gettype.call(o)=="[object Null]";     },     isDocument:function(){        return  gettype.call(o)=="[object Document]"|| [object HTMLDocument];     }     ........}

The simple method (recommended) for judging various data types in js is all the content shared by Alibaba Cloud xiaobian. I hope you can give us a reference and support for the customer's house.