A Simple Method for js to judge various data types

The following small series will provide you with a simple method (recommended) to judge various data types in js ). I think this is quite good. Now I will share it with you and give you a reference. Let's take a look at it together. We all know about js. There is a typeof 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] p 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.toString var  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 to give you a reference and support for PHP.

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