What is the use of jquery isEmptyObject() method?

In jquery, the isEmptyObject() method is used to determine whether the specified parameter is an empty object, that is, to detect whether it includes any enumerable (custom) properties. The syntax is "jQuery.isEmptyObject(object)"; The return value of this method is of Boolean type. If the specified parameter is an empty object, it returns true, otherwise it returns false.

The operating environment of this tutorial: windows7 system, jquery3.6.1 version, Dell G3 computer.

jQuery isEmptyObject() function introduction

jQuery.isEmptyObject() function is used to determine whether the specified parameter is an empty object.

The so-called "empty object" does not include any enumerable (custom) attributes. In short, this object has no properties that can be iterated through for...in.

Description: This function belongs to the global jQuery object. jQuery 1.4 added this static function.

---

Syntax:

jQuery.isEmptyObject( object )

Parameters:

##ParametersDescriptionobjectAny value of any type that needs to be judged.

Note: This parameter should always be a pure JavaScript Object, because other types (eg: DOM elements, raw strings/ numbers, host objects) may not yield consistent results across browsers. To determine whether an object is a pure JavaScript Object, you can use the $.isPlainObject() method.

Return value:

The return value of the jQuery.isEmptyObject() function is of Boolean type. If the specified parameter is an empty object, it returns true, otherwise it returns false.

isEmptyObject() function usage example

jQuery.isEmptyObject() is judged through a for...in loop. The source code is as follows :

isEmptyObject: function( obj ) {
    var name;
    for ( name in obj ) {
        return false;
    }
    return true;
}

The jQuery sample code of jQuery.isEmptyObject() function is as follows:

//在当前页面内追加换行标签和指定的HTML内容
function w( html ){
    document.body.innerHTML += "<br/>" + html;
}
 
 
 
w( $.isEmptyObject( { } ) ); // true
w( $.isEmptyObject( new Object() ) ); // true
 
w( $.isEmptyObject( [ 0 ] ) ); // false
w( $.isEmptyObject( { name: "CodePlayer"} ) ); // false
w( $.isEmptyObject( { sayHi: function(){} } ) ); // false
function User(){
 
}
User.prototype.word = "Hello";
// 自定义的原型对象上的属性也是可枚举的
w( $.isEmptyObject( new User() ) ); // false
 
 
/* 尽管在没有为空数组、Function、Number等内置对象添加自定义属性的情况下，它们也是不可枚举的，但是不推荐这么做。因为isEmptyObject()的参数应该始终是一个纯粹的Object */
 
// 数组中没有元素，也无法通过for...in迭代出属性
w( $.isEmptyObject( [ ] ) ); // true
// Function、Number、String等内置对象也无法通过for...in迭代出属性
w( $.isEmptyObject( function(){ alert("xxx") } ) ); // false

[Recommended learning:

jQuery video tutorial, web front-end video 】

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