How to accurately determine the data type of a variable in js-JS Tutorial-php.cn

How to accurately determine the data type of a variable in js

can be achieved through the toString() method.

(Recommended tutorial:js tutorial)

Function introduction:

toString() is the prototype method of Object. When this method is called, the current value is returned by default [[Class]] of the object. This is an internal property with the format [object Xxx] , where Xxx is the type of object.

For Object objects, calling toString() directly will return [object Object]. For other objects, you need to call / apply to return the correct type information.

Function syntax:

number.toString(radix)

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Code example:

Object.prototype.toString.call('') ; // [object String] Object.prototype.toString.call(1) ; // [object Number] Object.prototype.toString.call(true) ; // [object Boolean] Object.prototype.toString.call(Symbol()); //[object Symbol] Object.prototype.toString.call(undefined) ; // [object Undefined] Object.prototype.toString.call(null) ; // [object Null] Object.prototype.toString.call(new Function()) ; // [object Function] Object.prototype.toString.call(new Date()) ; // [object Date] Object.prototype.toString.call([]) ; // [object Array] Object.prototype.toString.call(new RegExp()) ; // [object RegExp] Object.prototype.toString.call(new Error()) ; // [object Error] Object.prototype.toString.call(document) ; // [object HTMLDocument] Object.prototype.toString.call(window) ; //[object global] window 是全局对象 global 的引用

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