JS method to judge whether the object is empty

1. Convert the json object into a json string, and then judge whether the string is "{}"

var data = {
    
    };
var b = (JSON.stringify(data) == "{}");
alert(b);

//true

2. for in loop judgment

var obj = {
    
    };

var b = function() {
    
    
	for(var key in obj) {
    
    
		return false;
	}
	return true;
}
alert(b());

//true

3. jQuery's isEmptyObject method

This method is that jquery encapsulates the 2 methods (for in), and needs to rely on jquery when using it

var data = {
    
    };
var b = $.isEmptyObject(data);
alert(b);

//true

4. Object.getOwnPropertyNames()

This method is to use the getOwnPropertyNames method of the Object object to obtain the property names in the object, store them in an array, and return the array object. We can judge whether the object is empty by judging the length of the array

Note: this method is not compatible with ie8

var data = {
    
    };
var arr = Object.getOwnPropertyNames(data);
alert(arr.length == 0);

//true

5. Use ES6's Object.keys() method

Similar to method 4, it is a new method of ES6, and the return value is also an array of attribute names in the object

var data = {
    
    };
var arr = Object.keys(data);
alert(arr.length == 0);

//true