Let’s talk about jQuery’s method of determining whether a variable is an object

With the continuous development of front-end technology, jQuery has become one of the important tools for front-end development. During the development process, we often need to determine the type of the variable, including determining whether the variable is an object type. Today, this article will introduce how to use jQuery to determine whether a variable is an object.

1. Determine variable type

Before introducing how to determine whether a variable is an object type, we need to understand how to determine the type of a variable. There are two methods in JavaScript to determine the type of a variable:

1.typeof operator: The typeof operator can be used to determine the type of a variable. The value it returns is a string representing the type of the variable. For example:

console.log(typeof 123); //输出number
console.log(typeof 'abc'); //输出string
console.log(typeof true); //输出boolean
console.log(typeof undefined); //输出undefined
console.log(typeof null); //输出object
console.log(typeof {}); //输出object
console.log(typeof []); //输出object

As can be seen from the above example, the typeof operator can determine most basic types, but it is not accurate for object types.

2.Object.prototype.toString() method: The Object.prototype.toString() method can be used to determine the type of an object. It returns a string in the format of "[object type]". For example:

console.log(Object.prototype.toString.call(123)); //输出[object Number]
console.log(Object.prototype.toString.call('abc')); //输出[object String]
console.log(Object.prototype.toString.call(true)); //输出[object Boolean]
console.log(Object.prototype.toString.call(undefined)); //输出[object Undefined]
console.log(Object.prototype.toString.call(null)); //输出[object Null]
console.log(Object.prototype.toString.call({})); //输出[object Object]
console.log(Object.prototype.toString.call([])); //输出[object Array]

As can be seen from the above example, the Object.prototype.toString() method can accurately determine the type of a variable, including basic types and object types.

2. Use jQuery to determine whether a variable is an object

We have already introduced how to determine the type of a variable. Next, we will introduce how to use jQuery to determine whether a variable is an object.

In jQuery, we can use the $.isPlainObject() method to determine whether a variable is a simple object (that is, an object that does not inherit the Object.prototype property). For example:

console.log($.isPlainObject({})); //输出true
console.log($.isPlainObject([])); //输出false
console.log($.isPlainObject(function(){})); //输出false
console.log($.isPlainObject(new Date())); //输出false
console.log($.isPlainObject(123)); //输出false
console.log($.isPlainObject(undefined)); //输出false
console.log($.isPlainObject(null)); //输出false
console.log($.isPlainObject('abc')); //输出false
console.log($.isPlainObject(true)); //输出false

As can be seen from the above example, the $.isPlainObject() method can accurately determine whether a variable is a simple object. Returns true if the variable is a simple object, false otherwise.

In addition to the $.isPlainObject() method, we can also use the $.type() method to determine the type of the variable, and determine whether the variable is an object type by determining whether the type string is "object" . For example:

console.log($.type({}) === 'object'); //输出true
console.log($.type([]) === 'object'); //输出true
console.log($.type(function(){}) === 'object'); //输出false
console.log($.type(new Date()) === 'object'); //输出true
console.log($.type(123) === 'object'); //输出false
console.log($.type(undefined) === 'object'); //输出false
console.log($.type(null) === 'object'); //输出false
console.log($.type('abc') === 'object'); //输出false
console.log($.type(true) === 'object'); //输出false

As can be seen from the above example, the $.type() method can accurately determine the type of a variable and determine whether the variable is an object type by comparing the type string.

3. Summary

This article introduces the method of using jQuery to determine whether a variable is an object. By using the $.isPlainObject() method or the $.type() method, we can accurately determine whether a variable is an object type, thereby implementing different logical operations. At the same time, during the development process, we can also choose the corresponding method according to actual needs to improve the efficiency and readability of the code.

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